Search Results: "ana"

10 September 2024

Ben Hutchings: FOSS activity in August 2024

Freexian Collaborators: Debian Contributions: Python 3 patches, OpenSSH GSS-API split, rebootstrap, salsa CI, etc. (by Anupa Ann Joseph)

Debian Contributions: 2024-08 Contributing to Debian is part of Freexian s mission. This article covers the latest achievements of Freexian and their collaborators. All of this is made possible by organizations subscribing to our Long Term Support contracts and consulting services.

Debian Python 3 patch review, by Stefano Rivera Last month, at DebConf, Stefano reviewed the current patch set of Debian s cPython packages with Matthias Klose, the primary maintainer until now. As a result of that review, Stefano re-reviewed the patchset, updating descriptions, etc. A few patches were able to be dropped, and a few others were forwarded upstream. One finds all sorts of skeletons doing reviews like this. One of the patches had been inactive (fortunately, because it was buggy) since the day it was applied, 13 years ago. One is a cleanup that probably only fixes a bug on HPUX, and is a result of copying code from xfree86 into Python 25 years ago. It was fixed in xfree86 a year later. Others support just Debian-specific functionality and probably never seemed worth forwarding. Or good cleanup that only really applies to Debian. A trivial new patch would allow Debian to multiarch co-install Python stable ABI dynamic extensions (like we can with regular dynamic extensions). Performance concerns are stalling it in review, at the moment.

DebConf 24 Organization, by Stefano Rivera Stefano helped organize DebConf 24, which concluded in early August. The event is run by a large entirely volunteer team. The work involved in making this happen is far too varied to describe here. While Freexian provides funding for 20% of collaborator time to spend on Debian-related work, it only covers a small fraction of contributions to time-intensive tasks like this. Since the end of the event, Stefano has been doing some work on the conference finances, and initiated the reimbursement process for travel bursaries.

Archive rebuilds on Debusine, by Stefano Rivera The recent setuptools 73 upload to Debian unstable removed the test subcommand, breaking many packages that were using python3 setup.py test in their Debian packaging. Stefano did a partial archive-rebuild using debusine.debian.net to find the regressions and file bugs. Debusine will be a powerful tool to do QA work like this for Debian in the future, but it doesn t have all the features needed to coordinate rebuild-testing, yet. They are planned to be fleshed out in the next year. In the meantime, Debusine has the building blocks to work through a queue of package building tasks and store the results, it just needs to be driven from outside the system. So, Stefano started working on a set of tools using the Debusine client API to perform archive rebuilds, found and tagged existing bugs, and filed many more.

OpenSSH GSS-API split, by Colin Watson Colin landed the first stage of the planned split of GSS-API authentication and key exchange support in Debian s OpenSSH packaging. In order to allow for smooth upgrades, the second stage will have to wait until after the Debian 13 (trixie) release; but once that s done, as upstream puts it, this substantially reduces the amount of pre-authentication attack surface exposed on your users sshd by default .

OpenSSL vs. cryptography, by Colin Watson Colin facilitated a discussion between Debian s OpenSSL team and the upstream maintainers of Python cryptography about a new incompatibility between Debian s OpenSSL packaging and cryptography s handling of OpenSSL s legacy provider, which was causing a number of build and test failures. While the issue remains open, the Debian OpenSSL maintainers have effectively reverted the change now, so it s no longer a pressing problem.

/usr-move, by Helmut Grohne There are less than 40 source packages left to move files to /usr, so what we re left with is the long tail of the transition. Rather than fix all of them, Helmut started a discussion on removing packages from unstable and filed a first batch. As libvirt is being restructured in experimental, we re handling the fallout in collaboration with its maintainer Andrea Bolognani. Since base-files validates the aliasing symlinks before upgrading, it was discovered that systemd has its own ideas with no solution as of yet. Helmut also proposed that dash checks for ineffective diversions of /bin/sh and that lintian warns about aliased files.

rebootstrap by Helmut Grohne Bootstrapping Debian for a new or existing CPU architecture still is a quite manual process. The rebootstrap project attempts to automate part of the early stage, but it still is very sensitive to changes in unstable. We had a number of fairly intrusive changes this year already. August included a little more fallout from the earlier gcc-for-host work where the C++ include search path would end up being wrong in the generated cross toolchain. A number of packages such as util-linux (twice), libxml2, libcap-ng or systemd had their stage profiles broken. e2fsprogs gained a cycle with libarchive-dev due to having gained support for creating an ext4 filesystem from a tar archive. The restructuring of glib2.0 remains an unsolved problem for now, but libxt and cdebconf should be buildable without glib2.0.

Salsa CI, by Santiago Ruano Rinc n Santiago completed the initial RISC-V support (!523) in the Salsa CI s pipeline. The main work started in July, but it was required to take into account some comments in the review (thanks to Ahmed!) and some final details in [!534]. riscv64 is the most recently supported port in Debian, which will be part of trixie. As its name suggests, the new build-riscv64 job makes it possible to test that a package successfully builds in the riscv64 architecture. The RISC-V runner (salsaci riscv64 runner 01) runs in a couple of machines generously provided by lab.rvperf.org. Debian Developers interested in running this job in their projects should enable the runner (salsaci riscv64 runner 01) in Settings / CI / Runners, and follow the instructions available at https://salsa.debian.org/salsa-ci-team/pipeline/#build-job-on-risc-v. Santiago also took part in discussions about how to optimize the build jobs and reviewed !537 to make the build-source job to only satisfy the Build-Depends and Build-Conflicts fields by Andrea Pappacoda. Thanks a lot to him!

Miscellaneous contributions
  • Stefano submitted patches for BeautifulSoup to support the latest soupsieve and lxml.
  • Stefano uploaded pypy3 7.3.17, upgrading the cPython compatibility from 3.9 to 3.10. Then ran into a GCC-14-related regression, which had to be ignored for now as it s proving hard to fix.
  • Colin released libpipeline 1.5.8 and man-db 2.13.0; the latter included foundations allowing adding an autopkgtest for man-db.
  • Colin upgraded 19 Python packages to new upstream versions (fixing 5 CVEs), fixed several other build failures, fixed a Python 3.12 compatibility issue in zope.security, and made python-nacl build reproducibly.
  • Colin tracked down test failures in python-asyncssh and Ruby resulting from certain odd /etc/hosts configurations.
  • Carles upgraded the packages python-ring-doorbell and simplemonitor to new upstream versions.
  • Carles started discussions and implementation of a tool (still in early days) named po-debconf-manager : a way for translators and reviewers to collaborate using git as a backend instead of mailing list; and submit the translations using salsa MR. More information next month.
  • Carles (dog-fooding po-debconf-manager ) reviewed debconf templates translated by a collaborator.
  • Carles reviewed and submitted the translation of apt .
  • Helmut sent 19 patches for improving cross building.
  • Helmut implemented the cross-exe-wrapper proposed by Simon McVittie for use with glib2.0.
  • Helmut detailed what it takes to make Perl s ExtUtils::PkgConfig suitable for cross building.
  • Helmut made the deletion of the root password work in debvm in all situations and implemented a test case using expect.
  • Anupa attended Debian Publicity team meeting and is moderating and posting on Debian Administrators LinkedIn group.
  • Thorsten uploaded package gutenprint to fix a FTBFS with gcc14 and package ipp-usb to fix a /usr-merge issue.
  • Santiago updated bzip2 to fix a long-standing bug that requested to include a pkg-config file. An important impact of this change is that it makes it possible to use Rust bindings for libbz2 by Sequoia, an implementation of OpenPGP.

8 September 2024

Jacob Adams: Linux's Bedtime Routine

How does Linux move from an awake machine to a hibernating one? How does it then manage to restore all state? These questions led me to read way too much C in trying to figure out how this particular hardware/software boundary is navigated. This investigation will be split into a few parts, with the first one going from invocation of hibernation to synchronizing all filesystems to disk. This article has been written using Linux version 6.9.9, the source of which can be found in many places, but can be navigated easily through the Bootlin Elixir Cross-Referencer: https://elixir.bootlin.com/linux/v6.9.9/source Each code snippet will begin with a link to the above giving the file path and the line number of the beginning of the snippet.

A Starting Point for Investigation: /sys/power/state and /sys/power/disk These two system files exist to allow debugging of hibernation, and thus control the exact state used directly. Writing specific values to the state file controls the exact sleep mode used and disk controls the specific hibernation mode1. This is extremely handy as an entry point to understand how these systems work, since we can just follow what happens when they are written to.

Show and Store Functions These two files are defined using the power_attr macro: kernel/power/power.h:80 
#define power_attr(_name) \
static struct kobj_attribute _name##_attr =     \
    .attr   =               \
        .name = __stringify(_name), \
        .mode = 0644,           \
     ,                  \
    .show   = _name##_show,         \
    .store  = _name##_store,        \
show is called on reads and store on writes. state_show is a little boring for our purposes, as it just prints all the available sleep states. kernel/power/main.c:657 
/*
 * state - control system sleep states.
 *
 * show() returns available sleep state labels, which may be "mem", "standby",
 * "freeze" and "disk" (hibernation).
 * See Documentation/admin-guide/pm/sleep-states.rst for a description of
 * what they mean.
 *
 * store() accepts one of those strings, translates it into the proper
 * enumerated value, and initiates a suspend transition.
 */
static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
			  char *buf)
 
	char *s = buf;
#ifdef CONFIG_SUSPEND
	suspend_state_t i;
	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
		if (pm_states[i])
			s += sprintf(s,"%s ", pm_states[i]);
#endif
	if (hibernation_available())
		s += sprintf(s, "disk ");
	if (s != buf)
		/* convert the last space to a newline */
		*(s-1) = '\n';
	return (s - buf);
state_store, however, provides our entry point. If the string disk is written to the state file, it calls hibernate(). This is our entry point. kernel/power/main.c:715 
static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
			   const char *buf, size_t n)
 
	suspend_state_t state;
	int error;
	error = pm_autosleep_lock();
	if (error)
		return error;
	if (pm_autosleep_state() > PM_SUSPEND_ON)  
		error = -EBUSY;
		goto out;
	 
	state = decode_state(buf, n);
	if (state < PM_SUSPEND_MAX)  
		if (state == PM_SUSPEND_MEM)
			state = mem_sleep_current;
		error = pm_suspend(state);
	  else if (state == PM_SUSPEND_MAX)  
		error = hibernate();
	  else  
		error = -EINVAL;
	 
 out:
	pm_autosleep_unlock();
	return error ? error : n;
kernel/power/main.c:688 
static suspend_state_t decode_state(const char *buf, size_t n)
 
#ifdef CONFIG_SUSPEND
	suspend_state_t state;
#endif
	char *p;
	int len;
	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;
	/* Check hibernation first. */
	if (len == 4 && str_has_prefix(buf, "disk"))
		return PM_SUSPEND_MAX;
#ifdef CONFIG_SUSPEND
	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++)  
		const char *label = pm_states[state];
		if (label && len == strlen(label) && !strncmp(buf, label, len))
			return state;
	 
#endif
	return PM_SUSPEND_ON;
Could we have figured this out just via function names? Sure, but this way we know for sure that nothing else is happening before this function is called.

Autosleep Our first detour is into the autosleep system. When checking the state above, you may notice that the kernel grabs the pm_autosleep_lock before checking the current state. autosleep is a mechanism originally from Android that sends the entire system to either suspend or hibernate whenever it is not actively working on anything. This is not enabled for most desktop configurations, since it s primarily for mobile systems and inverts the standard suspend and hibernate interactions. This system is implemented as a workqueue2 that checks the current number of wakeup events, processes and drivers that need to run3, and if there aren t any, then the system is put into the autosleep state, typically suspend. However, it could be hibernate if configured that way via /sys/power/autosleep in a similar manner to using /sys/power/state to manually enable hibernation. kernel/power/main.c:841 
static ssize_t autosleep_store(struct kobject *kobj,
			       struct kobj_attribute *attr,
			       const char *buf, size_t n)
 
	suspend_state_t state = decode_state(buf, n);
	int error;
	if (state == PM_SUSPEND_ON
	    && strcmp(buf, "off") && strcmp(buf, "off\n"))
		return -EINVAL;
	if (state == PM_SUSPEND_MEM)
		state = mem_sleep_current;
	error = pm_autosleep_set_state(state);
	return error ? error : n;
 
power_attr(autosleep);
#endif /* CONFIG_PM_AUTOSLEEP */
kernel/power/autosleep.c:24 
static DEFINE_MUTEX(autosleep_lock);
static struct wakeup_source *autosleep_ws;
static void try_to_suspend(struct work_struct *work)
 
	unsigned int initial_count, final_count;
	if (!pm_get_wakeup_count(&initial_count, true))
		goto out;
	mutex_lock(&autosleep_lock);
	if (!pm_save_wakeup_count(initial_count)  
		system_state != SYSTEM_RUNNING)  
		mutex_unlock(&autosleep_lock);
		goto out;
	 
	if (autosleep_state == PM_SUSPEND_ON)  
		mutex_unlock(&autosleep_lock);
		return;
	 
	if (autosleep_state >= PM_SUSPEND_MAX)
		hibernate();
	else
		pm_suspend(autosleep_state);
	mutex_unlock(&autosleep_lock);
	if (!pm_get_wakeup_count(&final_count, false))
		goto out;
	/*
	 * If the wakeup occurred for an unknown reason, wait to prevent the
	 * system from trying to suspend and waking up in a tight loop.
	 */
	if (final_count == initial_count)
		schedule_timeout_uninterruptible(HZ / 2);
 out:
	queue_up_suspend_work();
 
static DECLARE_WORK(suspend_work, try_to_suspend);
void queue_up_suspend_work(void)
 
	if (autosleep_state > PM_SUSPEND_ON)
		queue_work(autosleep_wq, &suspend_work);

The Steps of Hibernation

Hibernation Kernel Config It s important to note that most of the hibernate-specific functions below do nothing unless you ve defined CONFIG_HIBERNATION in your Kconfig4. As an example, hibernate itself is defined as the following if CONFIG_HIBERNATE is not set. include/linux/suspend.h:407 
static inline int hibernate(void)   return -ENOSYS;

Check if Hibernation is Available We begin by confirming that we actually can perform hibernation, via the hibernation_available function. kernel/power/hibernate.c:742 
if (!hibernation_available())  
	pm_pr_dbg("Hibernation not available.\n");
	return -EPERM;
kernel/power/hibernate.c:92 
bool hibernation_available(void)
 
	return nohibernate == 0 &&
		!security_locked_down(LOCKDOWN_HIBERNATION) &&
		!secretmem_active() && !cxl_mem_active();
nohibernate is controlled by the kernel command line, it s set via either nohibernate or hibernate=no. security_locked_down is a hook for Linux Security Modules to prevent hibernation. This is used to prevent hibernating to an unencrypted storage device, as specified in the manual page kernel_lockdown(7). Interestingly, either level of lockdown, integrity or confidentiality, locks down hibernation because with the ability to hibernate you can extract bascially anything from memory and even reboot into a modified kernel image. secretmem_active checks whether there is any active use of memfd_secret, and if so it prevents hibernation. memfd_secret returns a file descriptor that can be mapped into a process but is specifically unmapped from the kernel s memory space. Hibernating with memory that not even the kernel is supposed to access would expose that memory to whoever could access the hibernation image. This particular feature of secret memory was apparently controversial, though not as controversial as performance concerns around fragmentation when unmapping kernel memory (which did not end up being a real problem). cxl_mem_active just checks whether any CXL memory is active. A full explanation is provided in the commit introducing this check but there s also a shortened explanation from cxl_mem_probe that sets the relevant flag when initializing a CXL memory device. drivers/cxl/mem.c:186 
* The kernel may be operating out of CXL memory on this device,
* there is no spec defined way to determine whether this device
* preserves contents over suspend, and there is no simple way
* to arrange for the suspend image to avoid CXL memory which
* would setup a circular dependency between PCI resume and save
* state restoration.

Check Compression The next check is for whether compression support is enabled, and if so whether the requested algorithm is enabled. kernel/power/hibernate.c:747 
/*
 * Query for the compression algorithm support if compression is enabled.
 */
if (!nocompress)  
	strscpy(hib_comp_algo, hibernate_compressor, sizeof(hib_comp_algo));
	if (crypto_has_comp(hib_comp_algo, 0, 0) != 1)  
		pr_err("%s compression is not available\n", hib_comp_algo);
		return -EOPNOTSUPP;
The nocompress flag is set via the hibernate command line parameter, setting hibernate=nocompress. If compression is enabled, then hibernate_compressor is copied to hib_comp_algo. This synchronizes the current requested compression setting (hibernate_compressor) with the current compression setting (hib_comp_algo). Both values are character arrays of size CRYPTO_MAX_ALG_NAME (128 in this kernel). kernel/power/hibernate.c:50 
static char hibernate_compressor[CRYPTO_MAX_ALG_NAME] = CONFIG_HIBERNATION_DEF_COMP;
/*
 * Compression/decompression algorithm to be used while saving/loading
 * image to/from disk. This would later be used in 'kernel/power/swap.c'
 * to allocate comp streams.
 */
char hib_comp_algo[CRYPTO_MAX_ALG_NAME];
hibernate_compressor defaults to lzo if that algorithm is enabled, otherwise to lz4 if enabled5. It can be overwritten using the hibernate.compressor setting to either lzo or lz4. kernel/power/Kconfig:95 
choice
	prompt "Default compressor"
	default HIBERNATION_COMP_LZO
	depends on HIBERNATION
config HIBERNATION_COMP_LZO
	bool "lzo"
	depends on CRYPTO_LZO
config HIBERNATION_COMP_LZ4
	bool "lz4"
	depends on CRYPTO_LZ4
endchoice
config HIBERNATION_DEF_COMP
	string
	default "lzo" if HIBERNATION_COMP_LZO
	default "lz4" if HIBERNATION_COMP_LZ4
	help
	  Default compressor to be used for hibernation.
kernel/power/hibernate.c:1425 
static const char * const comp_alg_enabled[] =  
#if IS_ENABLED(CONFIG_CRYPTO_LZO)
	COMPRESSION_ALGO_LZO,
#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
	COMPRESSION_ALGO_LZ4,
#endif
 ;
static int hibernate_compressor_param_set(const char *compressor,
		const struct kernel_param *kp)
 
	unsigned int sleep_flags;
	int index, ret;
	sleep_flags = lock_system_sleep();
	index = sysfs_match_string(comp_alg_enabled, compressor);
	if (index >= 0)  
		ret = param_set_copystring(comp_alg_enabled[index], kp);
		if (!ret)
			strscpy(hib_comp_algo, comp_alg_enabled[index],
				sizeof(hib_comp_algo));
	  else  
		ret = index;
	 
	unlock_system_sleep(sleep_flags);
	if (ret)
		pr_debug("Cannot set specified compressor %s\n",
			 compressor);
	return ret;
 
static const struct kernel_param_ops hibernate_compressor_param_ops =  
	.set    = hibernate_compressor_param_set,
	.get    = param_get_string,
 ;
static struct kparam_string hibernate_compressor_param_string =  
	.maxlen = sizeof(hibernate_compressor),
	.string = hibernate_compressor,
 ;
We then check whether the requested algorithm is supported via crypto_has_comp. If not, we bail out of the whole operation with EOPNOTSUPP. As part of crypto_has_comp we perform any needed initialization of the algorithm, loading kernel modules and running initialization code as needed6.

Grab Locks The next step is to grab the sleep and hibernation locks via lock_system_sleep and hibernate_acquire. kernel/power/hibernate.c:758 
sleep_flags = lock_system_sleep();
/* The snapshot device should not be opened while we're running */
if (!hibernate_acquire())  
	error = -EBUSY;
	goto Unlock;
First, lock_system_sleep marks the current thread as not freezable, which will be important later7. It then grabs the system_transistion_mutex, which locks taking snapshots or modifying how they are taken, resuming from a hibernation image, entering any suspend state, or rebooting.

The GFP Mask The kernel also issues a warning if the gfp mask is changed via either pm_restore_gfp_mask or pm_restrict_gfp_mask without holding the system_transistion_mutex. GFP flags tell the kernel how it is permitted to handle a request for memory. include/linux/gfp_types.h:12 
 * GFP flags are commonly used throughout Linux to indicate how memory
 * should be allocated.  The GFP acronym stands for get_free_pages(),
 * the underlying memory allocation function.  Not every GFP flag is
 * supported by every function which may allocate memory.
In the case of hibernation specifically we care about the IO and FS flags, which are reclaim operators, ways the system is permitted to attempt to free up memory in order to satisfy a specific request for memory. include/linux/gfp_types.h:176 
 * Reclaim modifiers
 * -----------------
 * Please note that all the following flags are only applicable to sleepable
 * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them).
 *
 * %__GFP_IO can start physical IO.
 *
 * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the
 * allocator recursing into the filesystem which might already be holding
 * locks.
gfp_allowed_mask sets which flags are permitted to be set at the current time. As the comment below outlines, preventing these flags from being set avoids situations where the kernel needs to do I/O to allocate memory (e.g. read/writing swap8) but the devices it needs to read/write to/from are not currently available. kernel/power/main.c:24 
/*
 * The following functions are used by the suspend/hibernate code to temporarily
 * change gfp_allowed_mask in order to avoid using I/O during memory allocations
 * while devices are suspended.  To avoid races with the suspend/hibernate code,
 * they should always be called with system_transition_mutex held
 * (gfp_allowed_mask also should only be modified with system_transition_mutex
 * held, unless the suspend/hibernate code is guaranteed not to run in parallel
 * with that modification).
 */
static gfp_t saved_gfp_mask;
void pm_restore_gfp_mask(void)
 
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	if (saved_gfp_mask)  
		gfp_allowed_mask = saved_gfp_mask;
		saved_gfp_mask = 0;
	 
 
void pm_restrict_gfp_mask(void)
 
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	WARN_ON(saved_gfp_mask);
	saved_gfp_mask = gfp_allowed_mask;
	gfp_allowed_mask &= ~(__GFP_IO   __GFP_FS);

Sleep Flags After grabbing the system_transition_mutex the kernel then returns and captures the previous state of the threads flags in sleep_flags. This is used later to remove PF_NOFREEZE if it wasn t previously set on the current thread. kernel/power/main.c:52 
unsigned int lock_system_sleep(void)
 
	unsigned int flags = current->flags;
	current->flags  = PF_NOFREEZE;
	mutex_lock(&system_transition_mutex);
	return flags;
 
EXPORT_SYMBOL_GPL(lock_system_sleep);
include/linux/sched.h:1633 
#define PF_NOFREEZE		0x00008000	/* This thread should not be frozen */
Then we grab the hibernate-specific semaphore to ensure no one can open a snapshot or resume from it while we perform hibernation. Additionally this lock is used to prevent hibernate_quiet_exec, which is used by the nvdimm driver to active its firmware with all processes and devices frozen, ensuring it is the only thing running at that time9. kernel/power/hibernate.c:82 
bool hibernate_acquire(void)
 
	return atomic_add_unless(&hibernate_atomic, -1, 0);

Prepare Console The kernel next calls pm_prepare_console. This function only does anything if CONFIG_VT_CONSOLE_SLEEP has been set. This prepares the virtual terminal for a suspend state, switching away to a console used only for the suspend state if needed. kernel/power/console.c:130 
void pm_prepare_console(void)
 
	if (!pm_vt_switch())
		return;
	orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
	if (orig_fgconsole < 0)
		return;
	orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
	return;
The first thing is to check whether we actually need to switch the VT kernel/power/console.c:94 
/*
 * There are three cases when a VT switch on suspend/resume are required:
 *   1) no driver has indicated a requirement one way or another, so preserve
 *      the old behavior
 *   2) console suspend is disabled, we want to see debug messages across
 *      suspend/resume
 *   3) any registered driver indicates it needs a VT switch
 *
 * If none of these conditions is present, meaning we have at least one driver
 * that doesn't need the switch, and none that do, we can avoid it to make
 * resume look a little prettier (and suspend too, but that's usually hidden,
 * e.g. when closing the lid on a laptop).
 */
static bool pm_vt_switch(void)
 
	struct pm_vt_switch *entry;
	bool ret = true;
	mutex_lock(&vt_switch_mutex);
	if (list_empty(&pm_vt_switch_list))
		goto out;
	if (!console_suspend_enabled)
		goto out;
	list_for_each_entry(entry, &pm_vt_switch_list, head)  
		if (entry->required)
			goto out;
	 
	ret = false;
out:
	mutex_unlock(&vt_switch_mutex);
	return ret;
There is an explanation of the conditions under which a switch is performed in the comment above the function, but we ll also walk through the steps here. Firstly we grab the vt_switch_mutex to ensure nothing will modify the list while we re looking at it. We then examine the pm_vt_switch_list. This list is used to indicate the drivers that require a switch during suspend. They register this requirement, or the lack thereof, via pm_vt_switch_required. kernel/power/console.c:31 
/**
 * pm_vt_switch_required - indicate VT switch at suspend requirements
 * @dev: device
 * @required: if true, caller needs VT switch at suspend/resume time
 *
 * The different console drivers may or may not require VT switches across
 * suspend/resume, depending on how they handle restoring video state and
 * what may be running.
 *
 * Drivers can indicate support for switchless suspend/resume, which can
 * save time and flicker, by using this routine and passing 'false' as
 * the argument.  If any loaded driver needs VT switching, or the
 * no_console_suspend argument has been passed on the command line, VT
 * switches will occur.
 */
void pm_vt_switch_required(struct device *dev, bool required)
Next, we check console_suspend_enabled. This is set to false by the kernel parameter no_console_suspend, but defaults to true. Finally, if there are any entries in the pm_vt_switch_list, then we check to see if any of them require a VT switch. Only if none of these conditions apply, then we return false. If a VT switch is in fact required, then we move first the currently active virtual terminal/console10 (vt_move_to_console) and then the current location of kernel messages (vt_kmsg_redirect) to the SUSPEND_CONSOLE. The SUSPEND_CONSOLE is the last entry in the list of possible consoles, and appears to just be a black hole to throw away messages. kernel/power/console.c:16 
#define SUSPEND_CONSOLE	(MAX_NR_CONSOLES-1)
Interestingly, these are separate functions because you can use TIOCL_SETKMSGREDIRECT (an ioctl11) to send kernel messages to a specific virtual terminal, but by default its the same as the currently active console. The locations of the previously active console and the previous kernel messages location are stored in orig_fgconsole and orig_kmsg, to restore the state of the console and kernel messages after the machine wakes up again. Interestingly, this means orig_fgconsole also ends up storing any errors, so has to be checked to ensure it s not less than zero before we try to do anything with the kernel messages on both suspend and resume. drivers/tty/vt/vt_ioctl.c:1268 
/* Perform a kernel triggered VT switch for suspend/resume */
static int disable_vt_switch;
int vt_move_to_console(unsigned int vt, int alloc)
 
	int prev;
	console_lock();
	/* Graphics mode - up to X */
	if (disable_vt_switch)  
		console_unlock();
		return 0;
	 
	prev = fg_console;
	if (alloc && vc_allocate(vt))  
		/* we can't have a free VC for now. Too bad,
		 * we don't want to mess the screen for now. */
		console_unlock();
		return -ENOSPC;
	 
	if (set_console(vt))  
		/*
		 * We're unable to switch to the SUSPEND_CONSOLE.
		 * Let the calling function know so it can decide
		 * what to do.
		 */
		console_unlock();
		return -EIO;
	 
	console_unlock();
	if (vt_waitactive(vt + 1))  
		pr_debug("Suspend: Can't switch VCs.");
		return -EINTR;
	 
	return prev;
Unlike most other locking functions we ve seen so far, console_lock needs to be careful to ensure nothing else is panicking and needs to dump to the console before grabbing the semaphore for the console and setting a couple flags.

Panics Panics are tracked via an atomic integer set to the id of the processor currently panicking. kernel/printk/printk.c:2649 
/**
 * console_lock - block the console subsystem from printing
 *
 * Acquires a lock which guarantees that no consoles will
 * be in or enter their write() callback.
 *
 * Can sleep, returns nothing.
 */
void console_lock(void)
 
	might_sleep();
	/* On panic, the console_lock must be left to the panic cpu. */
	while (other_cpu_in_panic())
		msleep(1000);
	down_console_sem();
	console_locked = 1;
	console_may_schedule = 1;
 
EXPORT_SYMBOL(console_lock);
kernel/printk/printk.c:362 
/*
 * Return true if a panic is in progress on a remote CPU.
 *
 * On true, the local CPU should immediately release any printing resources
 * that may be needed by the panic CPU.
 */
bool other_cpu_in_panic(void)
 
	return (panic_in_progress() && !this_cpu_in_panic());
kernel/printk/printk.c:345 
static bool panic_in_progress(void)
 
	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
kernel/printk/printk.c:350 
/* Return true if a panic is in progress on the current CPU. */
bool this_cpu_in_panic(void)
 
	/*
	 * We can use raw_smp_processor_id() here because it is impossible for
	 * the task to be migrated to the panic_cpu, or away from it. If
	 * panic_cpu has already been set, and we're not currently executing on
	 * that CPU, then we never will be.
	 */
	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
console_locked is a debug value, used to indicate that the lock should be held, and our first indication that this whole virtual terminal system is more complex than might initially be expected. kernel/printk/printk.c:373 
/*
 * This is used for debugging the mess that is the VT code by
 * keeping track if we have the console semaphore held. It's
 * definitely not the perfect debug tool (we don't know if _WE_
 * hold it and are racing, but it helps tracking those weird code
 * paths in the console code where we end up in places I want
 * locked without the console semaphore held).
 */
static int console_locked;
console_may_schedule is used to see if we are permitted to sleep and schedule other work while we hold this lock. As we ll see later, the virtual terminal subsystem is not re-entrant, so there s all sorts of hacks in here to ensure we don t leave important code sections that can t be safely resumed.

Disable VT Switch As the comment below lays out, when another program is handling graphical display anyway, there s no need to do any of this, so the kernel provides a switch to turn the whole thing off. Interestingly, this appears to only be used by three drivers, so the specific hardware support required must not be particularly common. 
drivers/gpu/drm/omapdrm/dss
drivers/video/fbdev/geode
drivers/video/fbdev/omap2
drivers/tty/vt/vt_ioctl.c:1308 
/*
 * Normally during a suspend, we allocate a new console and switch to it.
 * When we resume, we switch back to the original console.  This switch
 * can be slow, so on systems where the framebuffer can handle restoration
 * of video registers anyways, there's little point in doing the console
 * switch.  This function allows you to disable it by passing it '0'.
 */
void pm_set_vt_switch(int do_switch)
 
	console_lock();
	disable_vt_switch = !do_switch;
	console_unlock();
 
EXPORT_SYMBOL(pm_set_vt_switch);
The rest of the vt_switch_console function is pretty normal, however, simply allocating space if needed to create the requested virtual terminal and then setting the current virtual terminal via set_console.

Virtual Terminal Set Console With set_console, we begin (as if we haven t been already) to enter the madness that is the virtual terminal subsystem. As mentioned previously, modifications to its state must be made very carefully, as other stuff happening at the same time could create complete messes. All this to say, calling set_console does not actually perform any work to change the state of the current console. Instead it indicates what changes it wants and then schedules that work. drivers/tty/vt/vt.c:3153 
int set_console(int nr)
 
	struct vc_data *vc = vc_cons[fg_console].d;
	if (!vc_cons_allocated(nr)   vt_dont_switch  
		(vc->vt_mode.mode == VT_AUTO && vc->vc_mode == KD_GRAPHICS))  
		/*
		 * Console switch will fail in console_callback() or
		 * change_console() so there is no point scheduling
		 * the callback
		 *
		 * Existing set_console() users don't check the return
		 * value so this shouldn't break anything
		 */
		return -EINVAL;
	 
	want_console = nr;
	schedule_console_callback();
	return 0;
The check for vc->vc_mode == KD_GRAPHICS is where most end-user graphical desktops will bail out of this change, as they re in graphics mode and don t need to switch away to the suspend console. vt_dont_switch is a flag used by the ioctls11 VT_LOCKSWITCH and VT_UNLOCKSWITCH to prevent the system from switching virtual terminal devices when the user has explicitly locked it. VT_AUTO is a flag indicating that automatic virtual terminal switching is enabled12, and thus deliberate switching to a suspend terminal is not required. However, if you do run your machine from a virtual terminal, then we indicate to the system that we want to change to the requested virtual terminal via the want_console variable and schedule a callback via schedule_console_callback. drivers/tty/vt/vt.c:315 
void schedule_console_callback(void)
 
	schedule_work(&console_work);
console_work is a workqueue2 that will execute the given task asynchronously.

Console Callback drivers/tty/vt/vt.c:3109 
/*
 * This is the console switching callback.
 *
 * Doing console switching in a process context allows
 * us to do the switches asynchronously (needed when we want
 * to switch due to a keyboard interrupt).  Synchronization
 * with other console code and prevention of re-entrancy is
 * ensured with console_lock.
 */
static void console_callback(struct work_struct *ignored)
 
	console_lock();
	if (want_console >= 0)  
		if (want_console != fg_console &&
		    vc_cons_allocated(want_console))  
			hide_cursor(vc_cons[fg_console].d);
			change_console(vc_cons[want_console].d);
			/* we only changed when the console had already
			   been allocated - a new console is not created
			   in an interrupt routine */
		 
		want_console = -1;
	 
...
console_callback first looks to see if there is a console change wanted via want_console and then changes to it if it s not the current console and has been allocated already. We do first remove any cursor state with hide_cursor. drivers/tty/vt/vt.c:841 
static void hide_cursor(struct vc_data *vc)
 
	if (vc_is_sel(vc))
		clear_selection();
	vc->vc_sw->con_cursor(vc, false);
	hide_softcursor(vc);
A full dive into the tty driver is a task for another time, but this should give a general sense of how this system interacts with hibernation.

Notify Power Management Call Chain kernel/power/hibernate.c:767 
pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION)
This will call a chain of power management callbacks, passing first PM_HIBERNATION_PREPARE and then PM_POST_HIBERNATION on startup or on error with another callback. kernel/power/main.c:98 
int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long val_down)
 
	int ret;
	ret = blocking_notifier_call_chain_robust(&pm_chain_head, val_up, val_down, NULL);
	return notifier_to_errno(ret);
The power management notifier is a blocking notifier chain, which means it has the following properties. include/linux/notifier.h:23 
 *	Blocking notifier chains: Chain callbacks run in process context.
 *		Callouts are allowed to block.
The callback chain is a linked list with each entry containing a priority and a function to call. The function technically takes in a data value, but it is always NULL for the power management chain. include/linux/notifier.h:49 
struct notifier_block;
typedef	int (*notifier_fn_t)(struct notifier_block *nb,
			unsigned long action, void *data);
struct notifier_block  
	notifier_fn_t notifier_call;
	struct notifier_block __rcu *next;
	int priority;
 ;
The head of the linked list is protected by a read-write semaphore. include/linux/notifier.h:65 
struct blocking_notifier_head  
	struct rw_semaphore rwsem;
	struct notifier_block __rcu *head;
 ;
Because it is prioritized, appending to the list requires walking it until an item with lower13 priority is found to insert the current item before. kernel/notifier.c:252 
/*
 *	Blocking notifier chain routines.  All access to the chain is
 *	synchronized by an rwsem.
 */
static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
					      struct notifier_block *n,
					      bool unique_priority)
 
	int ret;
	/*
	 * This code gets used during boot-up, when task switching is
	 * not yet working and interrupts must remain disabled.  At
	 * such times we must not call down_write().
	 */
	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_register(&nh->head, n, unique_priority);
	down_write(&nh->rwsem);
	ret = notifier_chain_register(&nh->head, n, unique_priority);
	up_write(&nh->rwsem);
	return ret;
kernel/notifier.c:20 
/*
 *	Notifier chain core routines.  The exported routines below
 *	are layered on top of these, with appropriate locking added.
 */
static int notifier_chain_register(struct notifier_block **nl,
				   struct notifier_block *n,
				   bool unique_priority)
 
	while ((*nl) != NULL)  
		if (unlikely((*nl) == n))  
			WARN(1, "notifier callback %ps already registered",
			     n->notifier_call);
			return -EEXIST;
		 
		if (n->priority > (*nl)->priority)
			break;
		if (n->priority == (*nl)->priority && unique_priority)
			return -EBUSY;
		nl = &((*nl)->next);
	 
	n->next = *nl;
	rcu_assign_pointer(*nl, n);
	trace_notifier_register((void *)n->notifier_call);
	return 0;
Each callback can return one of a series of options. include/linux/notifier.h:18 
#define NOTIFY_DONE		0x0000		/* Don't care */
#define NOTIFY_OK		0x0001		/* Suits me */
#define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
#define NOTIFY_BAD		(NOTIFY_STOP_MASK 0x0002)
						/* Bad/Veto action */
When notifying the chain, if a function returns STOP or BAD then the previous parts of the chain are called again with PM_POST_HIBERNATION14 and an error is returned. kernel/notifier.c:107 
/**
 * notifier_call_chain_robust - Inform the registered notifiers about an event
 *                              and rollback on error.
 * @nl:		Pointer to head of the blocking notifier chain
 * @val_up:	Value passed unmodified to the notifier function
 * @val_down:	Value passed unmodified to the notifier function when recovering
 *              from an error on @val_up
 * @v:		Pointer passed unmodified to the notifier function
 *
 * NOTE:	It is important the @nl chain doesn't change between the two
 *		invocations of notifier_call_chain() such that we visit the
 *		exact same notifier callbacks; this rules out any RCU usage.
 *
 * Return:	the return value of the @val_up call.
 */
static int notifier_call_chain_robust(struct notifier_block **nl,
				     unsigned long val_up, unsigned long val_down,
				     void *v)
 
	int ret, nr = 0;
	ret = notifier_call_chain(nl, val_up, v, -1, &nr);
	if (ret & NOTIFY_STOP_MASK)
		notifier_call_chain(nl, val_down, v, nr-1, NULL);
	return ret;
Each of these callbacks tends to be quite driver-specific, so we ll cease discussion of this here.

Sync Filesystems The next step is to ensure all filesystems have been synchronized to disk. This is performed via a simple helper function that times how long the full synchronize operation, ksys_sync takes. kernel/power/main.c:69 
void ksys_sync_helper(void)
 
	ktime_t start;
	long elapsed_msecs;
	start = ktime_get();
	ksys_sync();
	elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
	pr_info("Filesystems sync: %ld.%03ld seconds\n",
		elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
 
EXPORT_SYMBOL_GPL(ksys_sync_helper);
ksys_sync wakes and instructs a set of flusher threads to write out every filesystem, first their inodes15, then the full filesystem, and then finally all block devices, to ensure all pages are written out to disk. fs/sync.c:87 
/*
 * Sync everything. We start by waking flusher threads so that most of
 * writeback runs on all devices in parallel. Then we sync all inodes reliably
 * which effectively also waits for all flusher threads to finish doing
 * writeback. At this point all data is on disk so metadata should be stable
 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
 * just write metadata (such as inodes or bitmaps) to block device page cache
 * and do not sync it on their own in ->sync_fs().
 */
void ksys_sync(void)
 
	int nowait = 0, wait = 1;
	wakeup_flusher_threads(WB_REASON_SYNC);
	iterate_supers(sync_inodes_one_sb, NULL);
	iterate_supers(sync_fs_one_sb, &nowait);
	iterate_supers(sync_fs_one_sb, &wait);
	sync_bdevs(false);
	sync_bdevs(true);
	if (unlikely(laptop_mode))
		laptop_sync_completion();
It follows an interesting pattern of using iterate_supers to run both sync_inodes_one_sb and then sync_fs_one_sb on each known filesystem16. It also calls both sync_fs_one_sb and sync_bdevs twice, first without waiting for any operations to complete and then again waiting for completion17. When laptop_mode is enabled the system runs additional filesystem synchronization operations after the specified delay without any writes. mm/page-writeback.c:111 
/*
 * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
 * a full sync is triggered after this time elapses without any disk activity.
 */
int laptop_mode;
EXPORT_SYMBOL(laptop_mode);
However, when running a filesystem synchronization operation, the system will add an additional timer to schedule more writes after the laptop_mode delay. We don t want the state of the system to change at all while performing hibernation, so we cancel those timers. mm/page-writeback.c:2198 
/*
 * We're in laptop mode and we've just synced. The sync's writes will have
 * caused another writeback to be scheduled by laptop_io_completion.
 * Nothing needs to be written back anymore, so we unschedule the writeback.
 */
void laptop_sync_completion(void)
 
	struct backing_dev_info *bdi;
	rcu_read_lock();
	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
		del_timer(&bdi->laptop_mode_wb_timer);
	rcu_read_unlock();
As a side note, the ksys_sync function is simply called when the system call sync is used. fs/sync.c:111 
SYSCALL_DEFINE0(sync)
 
	ksys_sync();
	return 0;

The End of Preparation With that the system has finished preparations for hibernation. This is a somewhat arbitrary cutoff, but next the system will begin a full freeze of userspace to then dump memory out to an image and finally to perform hibernation. All this will be covered in future articles!
  1. Hibernation modes are outside of scope for this article, see the previous article for a high-level description of the different types of hibernation.
  2. Workqueues are a mechanism for running asynchronous tasks. A full description of them is a task for another time, but the kernel documentation on them is available here: https://www.kernel.org/doc/html/v6.9/core-api/workqueue.html 2
  3. This is a bit of an oversimplification, but since this isn t the main focus of this article this description has been kept to a higher level.
  4. Kconfig is Linux s build configuration system that sets many different macros to enable/disable various features.
  5. Kconfig defaults to the first default found
  6. Including checking whether the algorithm is larval? Which appears to indicate that it requires additional setup, but is an interesting choice of name for such a state.
  7. Specifically when we get to process freezing, which we ll get to in the next article in this series.
  8. Swap space is outside the scope of this article, but in short it is a buffer on disk that the kernel uses to store memory not current in use to free up space for other things. See Swap Management for more details.
  9. The code for this is lengthy and tangential, thus it has not been included here. If you re curious about the details of this, see kernel/power/hibernate.c:858 for the details of hibernate_quiet_exec, and drivers/nvdimm/core.c:451 for how it is used in nvdimm.
  10. Annoyingly this code appears to use the terms console and virtual terminal interchangeably.
  11. ioctls are special device-specific I/O operations that permit performing actions outside of the standard file interactions of read/write/seek/etc. 2
  12. I m not entirely clear on how this flag works, this subsystem is particularly complex.
  13. In this case a higher number is higher priority.
  14. Or whatever the caller passes as val_down, but in this case we re specifically looking at how this is used in hibernation.
  15. An inode refers to a particular file or directory within the filesystem. See Wikipedia for more details.
  16. Each active filesystem is registed with the kernel through a structure known as a superblock, which contains references to all the inodes contained within the filesystem, as well as function pointers to perform the various required operations, like sync.
  17. I m including minimal code in this section, as I m not looking to deep dive into the filesystem code at this time.

7 September 2024

Sergio Durigan Junior: Chatting in the 21st century

Several people have been asking me to explain and/or write about my solution for chatting nowadays. I realize that the current scenario is much more complex than, say, 10 or 20 years ago. Back then, this post would probably be more about the IRC client I used than about different chatting technologies. I have also spent a non trivial amount of time setting things up the way I want, so I understand that it s about time to write about my setup not only because I think it can be helpful to others, but also because I would like to document things for myself.

The backbone: Matrix I chose to use Matrix as the place where I integrate everything. Despite there being some heavy (and justified) criticism on the protocol itself, it serves me well for what I need right now. Obviously, I don t like the fact that I have to provide Matrix and all of its accompanying bridges a VPS with 4GB of RAM and 3 vCPUs, but I think that that ship has sailed, unfortunately. In an ideal world, I would be using XMPP and dedicating only a fraction of the resources I m using today to have a full chat system. And since I have been running my personal XMPP server for more than a decade now, I did try to find a solution that would allow me to keep using it, but unfortunately the protocol became almost a hobbyist thing, so there s that.

A few disclaimers I self-host everything, including my Matrix server. Much of what I did won t work if you don t self-host Matrix, so keep that in mind. This won t be a post teaching you how to deploy the services. My intention is to describe what I use and for what purpose. Also, as much as I try to use Debian packages for everything I do, I opted to deploy all services using a community-maintained Ansible playbook which is very well written and organized: matrix-docker-ansible-deploy. Last but not least, as I said above, you will likely need a machine with a good amount of RAM, CPU and storage, especially if you deploy Synapse as your Matrix homeserver (which is what I recommend if you plan to use the bridges I ll mention). My current VPS has 4GB of RAM, 3 vCPUs and 80GB of storage (of which I m currently using approximately 55GB).

Problem #1: my Matrix client(s) There are a lot of clients that can talk the Matrix protocol, but most of them are either web clients or GUI programs. I live on the terminal, more specifically inside Emacs, so I settled for the amazing ement.el Emacs mode. It works surprisingly well, but unfortunately doesn t support end-to-end encryption out of the box; for that, you have to hook it up with pantalaimon. Unfortunately, the project seems abandoned and therefore I don t recommend you to use it. I don t use it myself. When I have to reply some E2E encrypted message from another user, I go to my web browser and use my self-hosted Element client. It s a nuisance, but one that I m willing to accept because of security concerns. If you re into web clients and don t want to use Element (because it is heavy), you can try Cinny. It s lightweight and supports a decent set of features. If you re a terminal lover but don t use Emacs, you may want to try gomuks or iamb.

Problem #2: IRC bridging There are basically two types of IRC bridges for Matrix:
  • The regular and most used matrix-appservice-irc. This bridge takes Matrix to IRC (think of IRC users with the [m] suffix appended to their nicknames), and is what the matrix.org and other big homeservers (including matrix.debian.social) use. It s a complex service which allows thousands of Matrix users to connect to IRC networks, but that unfortunately has complex problems and is only worth using if you intend to host a community server.
  • A bouncer-like bridge called Heisenbridge. This is what I use personally. It takes IRC to Matrix, which means that people on IRC will not know that you re using Matrix. This bridge is much simpler, and because it acts like a bouncer it s pretty much impossible for it to cause problems with the IRC network.
Due to the fact that I sometimes like to use other IRC clients, I still run a regular ZNC bouncer, and I use Heisenbridge to connect to my ZNC. This means that I can use, e.g., ERC inside Emacs and my Matrix bridge at the same time. But you don t necessarily need to run another bouncer; you can simply use Heisenbridge and connect directly to the IRC network(s) you want. A word of caution, though: unlike ZNC, Heisenbridge doesn t support per-user configuration when you use it in bouncer mode. This is the reason why you need to self-host it, and why it s not possible to offer the service to other users (they would have access to your IRC network configuration otherwise). It s also worth talking about logs. I find that keeping logs of everything that goes on IRC has saved me a bunch of times, and so I find it really important to continue doing that. Unfortunately, neither ement.el nor Element support logging things out of the box (at least not that I know). This is also one of the reasons why I still keep my ZNC around: I configure it to log everything.

Problem #3: Telegram I don t use Telegram myself, but unfortunately several people from the Debian community do, especially in Brazil. There is a whole Debian community on Telegram, and I wanted to be able to bridge our Debian Matrix channels to their Telegram counterparts. I am currently using mautrix-telegram for that, and it s working great. You need someone with a Telegram account to configure their credentials so that the bridge can connect to it, but afterwards it s really easy to bridge channels together.

Problem #4: GitLab webhooks Something else I wanted to be able to do was to receive notifications regarding new issues, merge requests and other activities from Salsa. For this, I m using maubot, which is awesome and has a huge list of plugins. I m using the gitlab one.

Final thoughts Overall, I m satisfied with the setup I have now. It has certainly taken some time and effort to find the right tool for each problem I needed to solve, and I still feel like there are some rough edges to soften (like the fact that my Emacs client doesn t support E2E encryption out of the box, or the whole logging situation), but otherwise things are working fine and I haven t had any big problems with the deployment. You do have to be much more careful about stuff (for example, when I installed an unrelated service that hijacked my Apache configuration and made Matrix s federation silently stop working), though. If you have more specific questions about any part of my setup, shoot me an email and I ll do my best to help. Happy chatting!

4 September 2024

Reproducible Builds: Reproducible Builds in August 2024

Welcome to the August 2024 report from the Reproducible Builds project! Our reports attempt to outline what we ve been up to over the past month, highlighting news items from elsewhere in tech where they are related. As ever, if you are interested in contributing to the project, please visit our Contribute page on our website. Table of contents:
  1. LWN: The history, status, and plans for reproducible builds
  2. Intermediate Autotools build artifacts removed from PostgreSQL distribution tarballs
  3. Distribution news
  4. Mailing list news
  5. diffoscope
  6. Website updates
  7. Upstream patches
  8. Reproducibility testing framework

LWN: The history, status, and plans for reproducible builds The free software newspaper of record, Linux Weekly News, published an in-depth article based on Holger Levsen s talk, Reproducible Builds: The First Eleven Years which was presented at the recent DebConf24 conference in Busan, South Korea. Titled The history, status, and plans for reproducible builds and written by Jake Edge, LWN s article not only summarises Holger s talk and clarifies its message but it links to external information as well. Holger s original talk can also be watched on the DebConf24 webpage (direct .webm link and his HTML slides are available also). There are also a significant number of comments on LWN s page as well. Holger Levsen also headed a scheduled discussion session at DebConf24 on Preserving *other* build artifacts addressing a topic where a number of Debian packages are (or would like to) produce results that are neither the .deb files, the build logs nor the logs of CI tests. This is an issue for reproducible builds as this 4th type of build artifact are typically shipped within the binary .deb packages, and are invariably non-deterministic; thus making the .deb files unreproducible. (A direct .webm link and HTML slides are available).

Intermediate Autotools build artifacts removed from PostgreSQL distribution tarballs Peter Eisentraut wrote a detailed blog post on the subject of The new PostgreSQL 17 make dist . Like many projects, the PostgreSQL database has previously pre-built parts of its GNU Autotools build system: the reason for this is a mix of convenience and traditional practice . Peter astutely notes that this arrangement in the build system is quite tricky as:
You need to carefully maintain the different states of clean source code , partially built source code , and fully built source code , and the commands to transition between them.
However, Peter goes on to mention that:
a lot more attention is nowadays paid to the software supply chain. There are security and legal reasons for this. When users install software, they want to know where it came from, and they want to be sure that they got the right thing, not some fake version or some version of dubious legal provenance.
And cites the XZ Utils backdoor as a reason to care about transparent and reproducible ways of distributing and communicating a source tarball and provenance. Because of this, intermediate build artifacts are now henceforth essentially disallowed from PostgreSQL distribution tarballs.

Distribution news In Debian this month, 30 reviews of Debian packages were added, 17 were updated and 10 were removed this month adding to our knowledge about identified issues. One issue type was added by Chris Lamb, too. [ ] In addition, an issue was filed to update the Salsa CI pipeline (used by 1,000s of Debian packages) to no longer test for reproducibility with reprotest s build_path variation. Holger Levsen provided a rationale for this change in the issue, which has already been made to the tests being performed by tests.reproducible-builds.org.
In Arch Linux this month, Jelle van der Waa published a short blog post on the topic of Investigating creating reproducible images with mkosi, motivated by the desire to make it possible for anyone to re-recreate the official Arch cloud image bit-by-bit identical on their own machine as per [the] reproducible builds definition. In addition, Jelle filed a patch for pacman, the Arch Linux package manager, to respect the SOURCE_DATE_EPOCH environment variable when installing a package.
In openSUSE news, Bernhard M. Wiedemann published another report for that distribution.
In Android news, the IzzyOnDroid project added 49 new rebuilder recipes and now features 256 total reproducible applications representing 21% of the total offerings in the repository. IzzyOnDroid is an F-Droid style repository for Android apps[:] applications in this repository are official binaries built by the original application developers, taken from their resp. repositories (mostly GitHub).

Mailing list news From our mailing list this month:
  • Bernhard M. Wiedemann posted a brief message to the list with some helpful information regarding nondeterminism within Rust binaries, positing the use of the codegen-units = 16 default and resulting in a bug being filed in the Rust issue tracker. [ ]
  • Bernhard also wrote to the list, following up to a thread in November 2023, on attempts to make the LibreOffice suite of office applications build reproducibly. In the thread from this month, Bernhard could announce that the four patches previously mentioned have landed in LibreOffice upstream.
  • Fay Stegerman linked the mailing list to a thread she made on the Signal issue tracker regarding whether device-specific binaries [can] ever be considered meaningfully reproducible . In particular: the whole part about allow[ing] multiple third parties to come to a consensus on a correct result breaks down completely when correct is device-specific and not something everyone can agree on. [ ]
  • Developer kpcyrd posted an update for source code indexing project, whatsrc.org. Announcing that it now importing packages from live-bootstrap ( a usable Linux system [that is] created with only human-auditable, and wherever possible, human-written, source code ) into its database of provenance data.
  • Lastly, Mechtilde Stehmann posted an update to an earlier thread about how Java builds are not reproducible on the armhf architecture, enquiring how they might gain temporary access to such a machine in order to perform some deeper testing. [ ]

diffoscope diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb released versions 274, 275, 276 and 277, uploaded these to Debian, and made the following changes as well:
  • New features:
    • Strip ANSI escapes usually colour codes from the output of the Procyon Java decompiler. [ ]
    • Factor out a method for stripping ANSI escapes. [ ]
    • Append output from dumppdf(1) in more cases, avoiding situations where we fallback to a binary diff. [ ]
    • Add support for versions of Perl s IO::Compress::Zip version 2.212. [ ]
  • Bug fixes:
    • Also catch RuntimeError exceptions when importing the PyPDF library so that it, or, crucially, its transitive dependencies, cannot not cause diffoscope to traceback at runtime and build time. [ ]
    • Do not call marshal.load( ) of precompiled Python bytecode as it, alas, inherently unsafe. Replace for now with a brief summary of the code section of .pyc. [ ][ ]
    • Don t include excessive debug output when calling dumppdf(1). [ ]
  • Testsuite-related changes:
    • Don t bother to check version number in test_python.py: the fixture for this test is fixed. [ ][ ]
    • Update test_zip text fixtures and definitions to support new changes to the Perl IO::Compress library. [ ]
In addition, Mattia Rizzolo updated the available architectures for a number of test dependencies [ ] and Sergei Trofimovich fixed an issue to avoid diffoscope crashing when hashing directory symlinks [ ] and Vagrant Cascadian proposed GNU Guix updates for diffoscope versions 275 and 276 and 277.

Website updates There were a rather substantial number of improvements made to our website this month, including:
  • Alba Herrerias:
    • Substantially extend the guidance on the Contribute page. [ ]
  • Chris Lamb:
    • Set the future: true configuration value so we render all files and documents in the website, regardless of whether they have a date property in the future. After all, we don t re-generate the website on a timer, and have other ways of making unpublished, draft posts. [ ][ ]
  • Fay Stegerman:
  • hulkoba:
  • kpcyrd:
  • Mattia Rizzolo:
  • Pol Dellaiera:

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. In August, a number of changes were made by Holger Levsen, including:
  • Temporarily install the openssl-provider-legacy package for the Debian unstable environments for running diffoscope due to Debian bug #1078944. [ ][ ][ ][ ]
  • Mark Debian armhf architecture nodes as being down due to proxy down. [ ][ ]
  • Detect proxy failures. [ ][ ][ ]
  • Run the index-buildinfo for the builtin-pho script with the -q switch. [ ]
  • Disable all Arch Linux reproducible jobs. [ ]
In addition, Mattia Rizzolo updated the website configuration to install the ruby-jekyll-sitemap package as it is now used in the website [ ], Roland Clobus updated the script to build Debian live images to treat openQA issues as warnings [ ], and Vagrant Cascadian marked the cbxi4b node as down [ ].
If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

2 September 2024

Jonathan Carter: Debian Day South Africa 2024

Beer, cake and ISO testing amidst rugby and jazz band chaos On Saturday, the Debian South Africa team got together in Cape Town to celebrate Debian s 31st birthday and to perform ISO testing for the Debian 11.11 and 12.7 point releases.
We ran out of time to organise a fancy printed cake like we had last year, but our improvisation worked out just fine!
We thought that we had allotted plenty of time for all of our activities for the day, and that there would be plenty of time for everything including training, but the day zipped by really fast. We hired a venue at a brewery, which is usually really nice because they have an isolated area with lots of space and a big TV nice for presentations, demos, etc. But on this day, there was a big rugby match between South Africa and New Zealand, and as it got closer to the game, the place just got louder and louder (especially as a band started practicing and doing sound tests for their performance for that evening) and it turned out our space was also double-booked later in the afternoon, so we had to relocate.
Even amidst all the chaos, we ended up having a very productive day and we even managed to have some fun!
Four people from our local team performed ISO testing for the very first time, and in total we covered 44 test cases locally. Most of the other testers were the usual crowd in the UK, we also did a brief video call with them, but it was dinner time for them so we had to keep it short. Next time we ll probably have some party line open that any tester can also join.

Logo
We went through some more iterations of our local team logo that Tammy has been working on. They re turning out very nice and have been in progress for more than a year, I guess like most things Debian, it will be ready when it s ready!

Debian 11.11 and Debian 12.7 released, and looking ahead towards Debian 13 Both point releases tested just fine and was released later in the evening. I m very glad that we managed to be useful and reduce total testing time and that we managed to cover all the test cases in the end. A bunch of things we really wanted to fix by the time Debian 12 launched are now finally fixed in 12.7. There s still a few minor annoyances, but over all, Debian 13 (trixie) is looking even better than Debian 12 was around this time in the release cycle. Freeze dates for trixie has not yet been announced, I hope that the release team announces those sooner rather than later, also KDE Plasma 6 hasn t yet made its way into unstable, I ve seen quite a number of people ask about this online, so hopefully that works out. And by the way, the desktop artwork submissions for trixie ends in two weeks! More information about that is available on the Debian wiki if you re interested in making a contribution. There are already 4 great proposals.

Debian Local Groups Organising local events for Debian is probably easier than you think, and Debian does make funding available for events. So, if you want to grow Debian in your area, feel free to join us at -localgroups on the OFTC IRC network, also plumbed on Matrix at -localgroups:matrix.debian.social where we ll try to answer any questions you might have and guide you through the process! Oh and btw South Africa won the Rugby!

1 September 2024

Bits from Debian: Bits from the DPL

Dear Debian community, this are my bits from DPL for August. Happy Birthday Debian On 16th of August Debian celebrated its 31th birthday. Since I'm unable to write a better text than our great publicity team I'm simply linking to their article for those who might have missed it: https://bits.debian.org/2024/08/debian-turns-31.html Removing more packages from unstable Helmut Grohne argued for more aggressive package removal and sought consensus on a way forward. He provided six examples of processes where packages that are candidates for removal are consuming valuable person-power. I d like to add that the Bug of the Day initiative (see below) also frequently encounters long-unmaintained packages with popcon votes sometimes as low as zero, and often fewer than ten. Helmut's email included a list of packages that would meet the suggested removal criteria. There was some discussion about whether a popcon vote should be included in these criteria, with arguments both for and against it. Although I support including popcon, I acknowledge that Helmut has a valid point in suggesting it be left out. While I ve read several emails in agreement, Scott Kitterman made a valid point "I don't think we need more process. We just need someone to do the work of finding the packages and filing the bugs." I agree that this is crucial to ensure an automated process doesn t lead to unwanted removals. However, I don t see "someone" stepping up to file RM bugs against other maintainers' packages. As long as we have strict ownership of packages, many people are hesitant to touch a package, even for fixing it. Asking for its removal might be even less well-received. Therefore, if an automated procedure were to create RM bugs based on defined criteria, it could help reduce some of the social pressure. In this aspect the opinion of Niels Thykier is interesting: "As much as I want automation, I do not mind the prototype starting as a semi-automatic process if that is what it takes to get started." The urgency of the problem to remove packages was put by CharlesPlessy into the words: "So as of today, it is much less work to keep a package rotting than removing it." My observation when trying to fix the Bug of the Day exactly fits this statement. I would love for this discussion to lead to more aggressive removals that we can agree upon, whether they are automated, semi-automated, or managed by a person processing an automatically generated list (supported by an objective procedure). To use an analogy: I ve found that every image collection improves with aggressive pruning. Similarly, I m convinced that Debian will improve if we remove packages that no longer serve our users well. DEP14 / DEP18 There are two DEPs that affect our workflow for maintaining packages particularly for those who agree on using Git for Debian packages. DEP-14 recommends a standardized layout for Git packaging repositories, which benefits maintainers working across teams and makes it easier for newcomers to learn a consistent repository structure. DEP-14 stalled for various reasons. Sam Hartman suspected it might be because 'it doesn't bring sufficient value.' However, the assumption that git-buildpackage is incompatible with DEP-14 is incorrect, as confirmed by its author, Guido G nther. As one of the two key tools for Debian Git repositories (besides dgit) fully supports DEP-14, though the migration from the previous default is somewhat complex. Some investigation into mass-converting older formats to DEP-14 was conducted by the Perl team, as Gregor Hermann pointed out.. The discussion about DEP-14 resurfaced with the suggestion of DEP-18. Guido G nther proposed the title Encourage Continuous Integration and Merge Request-Based Collaboration for Debian Packages , which more accurately reflects the DEP's technical intent. Otto Kek l inen, who initiated DEP-18 (thank you, Otto), provided a good summary of the current status. He also assembled a very helpful overview of Git and GitLab usage in other Linux distros. More Salsa CI As a result of the DEP-18 discussion, Otto Kek l inen suggested implementing Salsa CI for our top popcon packages. I believe it would be a good idea to enable CI by default across Salsa whenever a new repository is created. Progress in Salsa migration In my campaign, I stated that I aim to reduce the number of packages maintained outside Salsa to below 2,000. As of March 28, 2024, the count was 2,368. Today, it stands at 2,187 (UDD query: SELECT DISTINCT count(*) FROM sources WHERE release = 'sid' and vcs_url not like '%salsa%' ;). After a third of my DPL term (OMG), we've made significant progress, reducing the amount in question (369 packages) by nearly half. I'm pleased with the support from the DDs who moved their packages to Salsa. Some packages were transferred as part of the Bug of the Day initiative (see below). Bug of the Day As announced in my 'Bits from the DPL' talk at DebConf, I started an initiative called Bug of the Day. The goal is to train newcomers in bug triaging by enabling them to tackle small, self-contained QA tasks. We have consistently identified target packages and resolved at least one bug per day, often addressing multiple bugs in a single package. In several cases, we followed the Package Salvaging procedure outlined in the Developers Reference. Most instances were either welcomed by the maintainer or did not elicit a response. Unfortunately, there was one exception where the recipient of the Package Salvage bug expressed significant dissatisfaction. The takeaway is to balance formal procedures with consideration for the recipient s perspective. I'm pleased to confirm that the Matrix channel has seen an increase in active contributors. This aligns with my hope that our efforts would attract individuals interested in QA work. I m particularly pleased that, within just one month, we have had help with both fixing bugs and improving the code that aids in bug selection. As I aim to introduce newcomers to various teams within Debian, I also take the opportunity to learn about each team's specific policies myself. I rely on team members' assistance to adapt to these policies. I find that gaining this practical insight into team dynamics is an effective way to understand the different teams within Debian as DPL. Another finding from this initiative, which aligns with my goal as DPL, is that many of the packages we addressed are already on Salsa but have not been uploaded, meaning their VCS fields are not published. This suggests that maintainers are generally open to managing their packages on Salsa. For packages that were not yet on Salsa, the move was generally welcomed. Publicity team wants you The publicity team has decided to resume regular meetings to coordinate their efforts. Given my high regard for their work, I plan to attend their meetings as frequently as possible, which I began doing with the first IRC meeting. During discussions with some team members, I learned that the team could use additional help. If anyone interested in supporting Debian with non-packaging tasks reads this, please consider introducing yourself to debian-publicity@lists.debian.org. Note that this is a publicly archived mailing list, so it's not the best place for sharing private information. Kind regards Andreas.

Guido G nther: Free Software Activities August 2024

Another short status update of what happened on my side last month. Quite a bit of time went into helping organize the FrOSCon FOSS on Mobile dev room (day 1, day 2, summary) but that was all worth it and fun - so was releasing Phosh 0.41.0 (which incidetally happened right before FrOScon). A three years old MR to xdg-spec to add call categories landed (thanks Matthias) allowing us to finally provide proper feedback for e.g. IM calls too. The rest was some OSK improvements (around Indic language support via varnam and layout configuration), some Cell Broadcast advancements (thanks to NGI0 for supporting this) but also some fixes. Here's the details: Phosh Phoc phosh-mobile-settings libphosh-rs phosh-osk-stub phosh-wallpapers meta-phosh phosh-recipes Debian Mobian ModemManager Calls gnome-bluetooth gnome-settings-daemon feedbackd Chatty Libcmatrix Eigenvalue kunifiedpush gir-rustdoc python-dbusmock matrix spec sound-theme spec varname-schemes FroSCon Help Development If you want to support my work see donations. This includes a list of hardware we want to improve support for. Thanks a lot to all current and past donors.

Russ Allbery: Review: Reasons Not to Worry

Review: Reasons Not to Worry, by Brigid Delaney
Publisher: Harper
Copyright: 2022
Printing: October 2023
ISBN: 0-06-331484-3
Format: Kindle
Pages: 295
Reasons Not to Worry is a self-help non-fiction book about stoicism, focusing specifically on quotes from Seneca, Epictetus, and Marcus Aurelius. Brigid Delaney is a long-time Guardian columnist who has written on a huge variety of topics, including (somewhat relevantly to this book) her personal experiences trying weird fads. Stoicism is having a moment among the sort of men who give people life advice in podcast form. Ryan Holiday, a former marketing executive, has made a career out of being the face of stoicism in everyone's podcast feed (and, of course, hosting his own). He is far from alone. If you pay attention to anyone in the male self-help space right now (Cal Newport, in my case), you have probably heard something vague about the "wisdom of the stoics." Given that the core of stoicism is easily interpreted as a strategy for overcoming your emotions with logic, this isn't surprising. Philosophies that lean heavily on college dorm room logic, discount emotion, and argue that society is full of obvious flaws that can be analyzed and debunked by one dude with some blog software and a free afternoon have been very popular in tech circles for the past ten to fifteen years, and have spread to some extent into popular culture. Intriguingly, though, stoicism is a system of virtue ethics, which means it is historically in opposition to consequentialist philosophies like utilitarianism, the ethical philosophy behind effective altruism and other related Silicon Valley fads. I am pretty exhausted with the whole genre of men talking to each other about how to live a better life Cal Newport by himself more than satisfies the amount of that I want to absorb but I was still mildly curious about stoicism. My education didn't provide me with a satisfying grounding in major historical philosophical movements, so I occasionally look around for good introductions. Stoicism also has some reputation as an anxiety-reduction technique, and I could use more of those. When I saw a Discord recommendation for Reasons Not to Worry that specifically mentioned its lack of bro perspective, I figured I'd give it a shot. Reasons Not to Worry is indeed not a bro book, although I would have preferred fewer appearances of the author's friend Andrew, whose opinions on stoicism I could not possibly care less about. What it is, though, is a shallow and credulous book that falls squarely in the middle of the lightweight self-help genre. Delaney is here to explain why stoicism is awesome and to convince you that a school of Greek and Roman philosophers knew exactly how you should think about your life today. If this sounds quasi-religious, well, I'll get to that. Delaney does provide a solid introduction to stoicism that I think is a bit more approachable than reading the relevant Wikipedia article. In her presentation, the core of stoicism is the practice of four virtues: wisdom, courage, moderation, and justice. The modern definition of "stoic" as someone who is impassive in the presence of pleasure or pain is somewhat misleading, but Delaney does emphasize a goal of ataraxia, or tranquility of mind. By making that the goal rather than joy or pleasure, stoicism tries to avoid the trap of the hedonic treadmill in favor of a more achievable persistent contentment. As an aside, some quick Internet research makes me doubt Delaney's summary here. Other material about stoicism I found focuses on apatheia and associates ataraxia with Epicureanism instead. But I won't start quibbling with Delaney's definitions; I'm not qualified and this review is already too long. The key to ataraxia, in Delaney's summary of stoicism, is to focus only on those parts of life we can control. She summarizes those as our character, how we treat others, and our actions and reactions. Everything else wealth, the esteem of our colleagues, good health, good fortune is at least partly outside of our control, and therefore we should enjoy it when we have it but try to be indifferent to whether it will last. Attempting to control things that are outside of our control is doomed to failure and will disturb our tranquility. Essentially all of this book is elaborations and variations on this theme, specialized to some specific area of life like social media, anxiety, or grief and written in the style of a breezy memoir. If you're familiar with modern psychological treatment frameworks like cognitive behavioral therapy or acceptance and commitment therapy, this summary of stoicism may sound familiar. (Apparently this is not an accident; the predecessor to CBT used stoicism as a philosophical basis.) Stoicism, like those treatment approaches, tries to refocus your attention on the things that you can improve and de-emphasizes the things outside of your control. This is a lot of the appeal, at least to me (and I think to Delaney as well). Hearing that definition, you may have some questions. Why those virtues specifically? They sound good, but all virtues sound good almost by definition. Is there any measure of your success in following those virtues outside your subjective feeling of ataraxia? Does the focus on only things you can control lead to ignoring problems only mostly outside of your control, where your actions would matter but only to a small degree? Doesn't this whole philosophy sound a little self-centered? What do non-stoic virtue ethics look like, and why do they differ from stoicism? What is the consequentialist critique of stoicism? This is where the shortcomings of this book become clear: Delaney is not very interested in questions like this. There are sections on some of those topics, particularly the relationship between stoicism and social justice, but her treatment is highly unsatisfying. She raises the question, talks about her doubts about stoicism's applicability, and then says that, after further thought, she decided stoicism is entirely consistent with social justice and the stoics were right after all. There is a little bit more explanation than that, but not much. Stoicism can apparently never be wrong; it can only be incompletely understood. Self-help books often fall short here, and I suspect this may be what the audience wants. Part of the appeal of the self-help genre is artificial certainty. Becoming a better manager, starting a business, becoming more productive, or working out an entire life philosophy are not problems amenable to a highly approachable and undemanding book. We all know that at some level, but the seductive allure of the self-help genre is the promise of simplifying complex problems down to a few approachable bullet points. Here is a life philosophy in a neatly packaged form, and if you just think deeply about its core principles, you will find they can be applied to any situation and any doubts you were harboring will turn out to be incorrect. I am all too familiar with this pattern because it's also how fundamentalist Christianity works. The second time Delaney talked about her doubts about the applicability of stoicism and then claimed a few pages later that those doubts disappeared with additional thought and discussion, my radar went off. This book was sounding less like a thoughtful examination of one specific philosophy out of many and more like the soothing adoption of religious certainty by a convert. I was therefore entirely unsurprised when Delaney all but says outright in the epilogue that she's adopted stoicism as her religion and approaches it with the same dedicated practice that she used to bring to Catholicism. I think this is where a lot of self-help books end up, although most of them don't admit it. There's nothing wrong with this, to be clear. It sounds like she was looking for a non-theistic religion, found one that she liked, and is excited to tell other people about it. But it's a profound mismatch with what I was looking for in an introduction to stoicism. I wanted context, history, and a frank discussion of the problems with adopting philosophy to everyday issues. I also wanted some acknowledgment that it is highly unlikely that a few men who lived 2000 years ago in a wildly different social context, and with drastically limited information about cultures other than their own, figured out a foolproof recipe for how to approach life. The subsequent two millennia of philosophical debates prove that stoicism didn't end the argument, and that a lot of other philosophers thought that stoicism got a few things wrong. You would never know that from this book. What I wanted is outside the scope of this sort of undemanding self-help book, though, and this is the problem that I keep having with philosophy. The books I happen across are either nigh-incomprehensibly dense and academic, or they're simplified into catechism. This was the latter. That's probably more the fault of my reading selection than it is the fault of the book, but it was still annoying. What I will say for this book, and what I suspect may be the most useful property of self-help books in general, is that it prompts you to think about basic stoic principles without getting in the way of your thoughts. It's like background music for the brain: nothing Delaney wrote was very thorny or engaging, but she kept quietly and persistently repeating the basic stoic formula and turning my thoughts back to it. Some of those thoughts may have been useful? As a source of prompts for me to ponder, Reasons Not to Worry was therefore somewhat successful. The concept of not trying to control things outside of my control is simple but valid, and it probably didn't hurt me to spend a week thinking about it. "It kind of works as an undemanding meditation aid" is not a good enough reason for me to recommend this book, but maybe that's what someone else is looking for. Rating: 5 out of 10

31 August 2024

Russell Coker: Links August 2024

Bruce Schneier and Kim C rdova wrote an insightful article about the changes that corporations make to culture as technical debt [1]. We need anti-trust laws to be enforced before it s too late! Bruce Schneier posted the transcript of an insightful lecture he gave on rethinking democracy for the age of AI [2]. Cory Doctorow wrote an insightful blog post about companies that are too big to care [3]. We need to break up those monopolies. Science Alert has an interesting article on plans to get renewable energy by drilling into the magma chamber of an active volcano [4]. What I want to know is whether using the energy could reduce the power of an eruption or even prevent it from happening. Bruce Schneier wrote an interesting article about Crowdstrike and the market incentives for brittle systems [5]. Also we need to have more formally proven software and more use of systems like seL4. Dave s Garage on YouTube has an interesting video about modern Mainframes [6]. Their IO capacity dwarfs the memory bandwidth of most PC servers. Framework has an interesting YouTube video about the process of developing a RISC-V motherboard for their laptops [7]. The documentary series Who Broke Britain by ABC news gives a good insight into the harm caused by austerity policies [8]. Rolling Stone has an interesting story about the consequences of being a CIA agent in al Quaeda [9].
Related posts:
  1. Links July 2024 Interesting Scientific American article about the way that language shapes...
  2. Links June 2024 Modos Labs have released the design of an e-ink display...
  3. Links August 2023 This is an interesting idea from Bruce Schneier, an AI...

30 August 2024

Sahil Dhiman: Debconf24 Busan

DebConf24 was held in Busan, South Korea, from July 28th to August 4th 2024 and preceded by DebCamp from July 21st to July 27th. This was my second IRL DebConf (DC) and fourth one in total. I started in Debian with a DebConf, so its always an occasion when one happens. This year again, I worked in fundraising team, working to raise funds from International sponsors. We did manage to raise good enough funding, albeit less than budgeted. Though, the local Korean team was able to connect and gather many Governmental sponsors, which was quite surprising for me. I wasn t seriously considering attending DebConf until I discussed this with Nilesh. More or less, his efforts helped push me through the whole process. Thanks, Nilesh, for this. In March, I got my passport and started preparing documents for South Korean visa. It did require quite a lot of paper work but seeing South Korea s s fresh passport visa rejection rate, I had doubts about visa acceptance. The visa finally got approved, which could be attributed to great documentation and help from DebConf visa team. This was also my first trip outside India, and this being to DebConf made many things easy. Most stuff were documented on DebConf website and wiki. Asking some query got immediate responses from someone in the DebConf channels. We then booked a direct flight from Delhi, reaching Seoul in the morning. With good directions from Sourab TK who had reached Seoul a few hours earlier, we quickly got Korean Won, local SIM and T Money card (transportation card) and headed towards Seoul by AREX, airport metro. We spent the next two days exploring Seoul, which is huge. It probably has the highest number of skyscrapers I have ever seen. The city has a good mix of modern and ancient culture. We explored various places in Seoul including Gyeongbokgung Palace, Statue of King Sejong, Bukchon Hanok village, N Seoul Tower and various food markets which were amazing. A Street in Seoul
A Street in Seoul
Next, we headed to Busan for DebConf using KTX (Korean high speed rail). (Fun fact, slogan for City of Busan is Busan is Good .) South Korea has a good network of frequently running high speed trains. We had pre-booked our tickets because, despite the frequency, trains were sold out most of the time. KTX ride was quite smooth, despite travelling at 300 Kmph at times through Korean countryside and long mountain tunnels. View from Dorm Room
PKNU Entrance
The venue for DebConf was Pukyong National University (PKNU), Daeyeon Campus. PKNU had two campuses in the Busan and some folks ended up in wrong campus too. With good help and guidance from the front desk, we got our dormitory rooms assigned. Dorms here were quite different, ie: View from Dorm Room
View from Dorm Room
Settling in was easy. We started meeting familiar folks after almost a year. The long conversations started again. Everyone was excited for DebConf. Like everytime, the first day was full of action (and chaos). Meet and greet, volunteers check in, video team running around and fixing stuff and things working (or not). There were some interesting talks and sponsors stalls. After day one, things more or less settled down. I again volunteered for video team stuff and helped in camera operations and talk directions, which is always fun. As the tradition applies, saw few talks live on stream too sitting in the dorm room during the conf, which is always fun, when too tired to get ready and go out. From Talk Director's chair
From Talk Director's chair
DebConf takes care of food needs for vegan/vegetarianism folks well, of which I m one. I got to try different food items, which was quite an experience. Tried using chopsticks again which didn t work, which I later figured that handling metal ones were more difficult. We had late night ramens and wooden chopsticks worked perfectly. One of the days, we even went out to an Indian restaurant to have some desi aloo paratha, paneer dishes, samosas and chai (milk tea). I wasn t particularly craving desi food but wasn t able to get something according to my taste so went there. As usual Bits from DPL talk was packed
As usual Bits from DPL talk was packed
For day trip, I went to Ulsan. San means mountains in Korean. Ulsan is a port city with many industries including Hyundai car factory, petrochemical industry, paint industry, ship building etc. We saw bamboo forest, Ulsan tower (quite a view towards Ulsan port), whale village, Ulsan Onggi Museum and the sea (which was beautiful). The beautiful sea
The beautiful sea

View from Ulsan Bridge Observatory
View from Ulsan Bridge Observatory
Amongst the sponsors, I was most interested in our network sponsors, folks who were National research and education networks (NREN) here. We had two network sponsors, KOREN and KREONET, thanks to efforts by local team. Initially it was discussed that they ll provide 20G uplink each, so 40G in total, which was whopping but by the time the closing talk happened, we got to know we had 200G uplink to the Internet. This was a massive update to last year when we had 1G main and 100M backup link. 200G wasn t what is required, but it was massive capacity and IIRC from the talk, we peaked at around 500M in usage, but it s always fun to have astronomical amount of bandwidth for bragging rights ;) Various mascots in attendance
Various mascots in attendance

Video and Network stats. Screengrab from closing ceremony
Video and Network stats. Screengrab from closing ceremony
Now let s talk about things I found interesting about South Korea in general: Gyeongbokgung Palace Entrance Gyeongbokgung Palace Entrance Gyeongbokgung Palace Entrance
Grand Gyeongbokgung Palace, Seoul

Starfield Library
Starfield Library, Seoul
If one has to get the whole DebConf experience, it s better to attend DebCamp as well because that s when you can sit and interact with everyone better. As DebConf starts, everyone gets busy in various talks and events and things take a pace. DebConf days literally fly. This year, attending DebConf in person was a different experience. Attending DebConf without any organizational work/stress so was better, and I was able to understand working of different Debian team and workflows better while also identified a few where I would like to join and help. A general conclusion was that almost all Debian teams needs more folks to help out. So if someone want to join, they can probably reach out to the team, and would be able to onboard new folks. Though this would require some patience. Kudos to the Korean team who were able to pull off this event under this tight timeline and thanks for all the hospitality. DebConf24 Group Photo
DebConf24 Group Photo. Click to enlarge.
Credits - Aigars Mahinovs
This whole experience expanded my world view. There s so much to see and explore and understand. Looking forward to DebConf25 in Brest, France. PS - Shoutout to abbyck (aka hamCK)!

Russ Allbery: Review: Thornhedge

Review: Thornhedge, by T. Kingfisher
Publisher: Tor
Copyright: 2023
ISBN: 1-250-24410-2
Format: Kindle
Pages: 116
Thornhedge is a fantasy novella by T. Kingfisher, the pen name that Ursula Vernon uses for her adult writing. It won the 2024 Hugo Award for best novella. No matter how much my brain wants to misspell the title, it is a story about a hedge, not a Neolithic earthwork.
The fairy was the greenish-tan color of mushroom stems and her skin bruised blue-black, like mushroom flesh. She had a broad, frog-like face and waterweed hair. She was neither beautiful nor made of malice, as many of the Fair Folk are said to be.
There is a princess asleep in a tower, surrounded by a wall of thorns. Toadling's job is to keep anyone from foolishly breaking in. At first, it was a constant struggle and all that she could manage, but with time, the flood of princes slowed to a trickle. A road was built and abandoned. People fled. There was a plague. With any luck, the tower was finally forgotten. Then a knight shows up. Not a very rich knight, nor a very successful knight. Just a polite and very persistent knight who wants to get into the tower that Toadling does not want him to get into. As you might have guessed, this is a Sleeping Beauty retelling. As you may have also guessed from the author, or from the cover text that says "not all curses should be broken," this version is a bit different. How and why it departs from the original is a surprise that slowly unfolds over the course of the story, in parallel to a delicate, cautious, and delightfully kind-hearted conversation between the knight and the fairy. If you have read a T. Kingfisher story before, particularly one of her fractured fairy tales, you know what to expect. Toadling is one of her typical well-meaning, earnest, slightly awkward protagonists who is just trying to do the right thing in a confusing world full of problems and dangers. She's constantly overwhelmed and yet she keeps going, because what else is there to do. Like a lot of Kingfisher's writing, it's a story about quiet courage from someone who doesn't consider herself courageous. One of the twists this time is that the knight is a character from a similar vein: doggedly unwilling to leave any problem alone, but equally determined to try to be kind. The two of them together make for a story with a gentle and rather melancholy tone. We do, eventually, learn the whole backstory of the tower, the wall of thorns, and Toadling. There is a god, a rather memorable one, who is frustratingly cryptic in the way that gods are. There are monsters who are more loving than most humans. There are humans who turn out to be surprisingly decent when it matters. And, like most of Kingfisher's writing, there is a constant awareness of how complicated the world is, how full it is of people who are just trying to get through each day, and how heavy of burdens people can shoulder when they don't see another way. This story pulled me right in. It is not horror, although there are a few odd bits like there always are in Kingfisher stories. Your largest risk as a reader is that it might make you cry if stories about earnest people doing their best in overwhelming situations hit you that way. My primary complaint is that there was nowhere near enough ending for me. After everything I learned about the characters, I wanted to spend some time with them outside of the bounds of the story. Kingfisher points the reader in a direction and then leaves the rest to your imagination, and I can see why she chose that story construction, but I wanted more catharsis than I got. That complaint aside, this is quintessential T. Kingfisher, and I am unsurprised that it won a Hugo. If you've read any of her other fractured fairy tales, or the 2023 Hugo winner for best novel, you know the sort of stories she tells, and you probably know whether you will like this. I am one of the people who like this. Rating: 8 out of 10

29 August 2024

Michael Ablassmeier: proxmox backup S3 proxy

A few weeks ago Tiziano Bacocco started a small project to implement a (golang) proxy that allows to store proxmox backups on S3 compatible storage: pmoxs3backuproxy, a feature which the current backup server does not have. I wanted to have a look at the Proxmox Backup Server implementation for a while, so i jumped on the wagon and helped with adding most of the API endpoints required to seamlessly use it as drop-in replacement in PVE. The current version can be configured as storage backend in PVE. You can then schedule your backups to the S3 storage likewise. It now supports both the Fixed index format required to create virtual machine backups and the Dynamic index format, used by the regular proxmox-backup-client for file and container backups. (full and incremental) The other endpoints like adding notes, removing or protecting backups, mounting images using the PVE frontend (or proxmox-backup-client) work too. It comes with a garbage collector that does prune the backup storage if snapshots expire and runs integrity checks on the data. You can also configure it as so called remote storage in the Proxmox Backup server itself and pull back complete buckets using proxmox-backup-manager pull , if your local datastore crashes. I think it will become more interesting if future proxmox versions will allow to push backups to other stores, too.

28 August 2024

Debian Brasil: Debian Day 2024 em Bel m e Po os de Caldas - Brasil

por Paulo Henrique de Lima Santana (phls) Listamos abaixo os links para os relatos e not cias do Debian Day 2024 realizado em Bel m e Po os de Caldas:

27 August 2024

Russ Allbery: Review: Dark Horse

Review: Dark Horse, by Michelle Diener
Series: Class 5 #1
Publisher: Eclipse
Copyright: June 2015
ISBN: 0-9924559-3-6
Format: Kindle
Pages: 366
Dark Horse is a science fiction romance novel, the first of a five book series as of this writing. It is self-published, although it is sufficiently well-edited and packaged that I had to do some searching to confirm that. Rose was abducted by aliens. The Tecrans picked her up along with a selection of Earth animals, kept her in a cell in their starship, and experimented on her. As the book opens, she has managed to make her escape with the aid of an AI named Sazo who was also imprisoned on the Tecran ship. Sazo dealt with the Tecrans, dropped the ship in the middle of Grih territory, and then got Rose and most of the animals on shuttles to a nearby planet. Dav Jallan is the commander of the ship the Grih sent to investigate the unexplained appearance of a Class 5 Tecran warship in the middle of their territory. The Grih and the Tecran, along with three other species, are members of the United Council, which means in theory they're all at peace. With the Tecran, that theory is often strained. Dav is not going to turn down one of their highly-advanced Class 5 warships delivered to him on a silver platter. There is only the matter of the unexpected cargo, the first orange dots (indicating unknown life forms) that most of the Grih have ever seen. There is a romance. That romance did not work for me. I thought it was highly unprofessional on Dav's part and a bit too obviously constructed on the author's part. It also leans on the subgenre convention that aliens can be remarkably physically similar and sexually compatible, which always causes problems for my suspension of disbelief even though I know it's no less plausible than faster-than-light travel. Despite that, I had so much fun with this book! It was absolutely delightful and weirdly grabby in a way that caught me by surprise. I was skimming some parts of it to write this review and found myself re-reading multiple pages before I dragged myself back on task. I think the most charming part of this book is that the United Council has a law called the Sentient Beings Agreement that makes what the Tecran were doing extremely illegal, and the Grih and the other non-Tecran aliens take this very seriously and with a refreshing lack of cynicism. Rose has a typical human reaction to ending up in a place where she doesn't know the rules and isn't entirely an expected guest. She almost reflexively smoothes over miscommunications and tensions, trying to adapt to their expectations. And then, repeatedly, the Grih realize how much work she's doing to adapt to them, feel enraged at the Tecran and upset that they didn't understand or properly explain something, and find some way to make Rose feel more comfortable. It's surprisingly soothing and comforting to read. It occurred to me in several places that Dark Horse could be read as a wish-fulfillment fantasy of what life as a woman could be like if men took their fair share of the mental load. (This concept is usually applied to housework, but I think it generalizes to other social and communication contexts.) I suspect this was not an accident. There is a lot of wish fulfillment in this book. The Grih are very human-like but hunky, which is convenient for the romance subplot. They struggle to sing, value music exceptionally highly, and consider Rose's speaking voice beautifully musical. Her typical human habit of singing to herself is a source of immediate and almost overwhelming fascination. The supplies Rose takes from the Tecran ship when she flees just happen to be absurdly expensive scented shampoo and equally expensive luxury adaptable clothing. The world she lands on, and the Grih ship, are low-gravity compared to Earth, so Rose is unusually strong for her size. Grih military camouflage has no effect on her human vision. The book is set up to make Rose special. If that type of wish fulfillment is going to grate, wait on this book until you're more in the mood for it. But I like wish fulfillment books when they're done well. Part of why I like to read is to imagine a better world. And Rose isn't doted on; despite their hospitality, she's constantly underestimated by the Grih. Even with their deep belief in the Sentient Beings Agreement, they find it hard to believe that an unknown sentient, even an advanced sentient, is really their equal. Their concern at the start is somewhat patronizing, so watching Rose constantly surprise them delighted the part of my brain that likes both competence porn and deserved reversals, even though the competence here is often due to accidents of biology. It helps that Diener tells the story in alternating perspectives, so the reader first watches Rose do something practical and straightforward from her perspective and then gets to enjoy the profound surprise and chagrin of the aliens. There is a plot beneath this first contact story, and beyond the political problem of figuring out what to do with Rose and the Tecran. Sazo, Rose's AI friend, does not want the Grih to know he exists. He has a history that Rose does not know about and may not be entirely safe. As the political situation with the Tecran escalates, Sazo is pursuing goals of his own, and Rose has a firm opinion about where her loyalties should lie. The resolution is nothing ground-breaking as far as SF goes, but I thought it was satisfyingly tense and complex. Dark Horse leaves obvious room for a sequel, but it comes to a satisfying conclusion. The writing is serviceable, particularly once you get into the story. I would not call it great, and it's not going to win any literary awards, but it didn't interfere with my enjoyment of the story. This is not the sort of book that will make anyone's award list, but it is easily in the top five of books I had the most fun reading this year. Maybe save it for when you're looking for something light and wholesome and don't mind some rather obvious tropes, but if you're in the mood for imagining people who take laws seriously and sincerely try to help other people, I found this an utterly delightful way to pass the time. I immediately bought the sequel. Recommended. Followed by Dark Deeds. Rating: 8 out of 10

24 August 2024

Russell Coker: Wifi 6E Mesh

I am looking into getting a Wifi mesh network. The aim is to use it for providing access to devices through my home especially for devices on the congested 2.4GHz frequency. Ideally I want 6GHz Wifi6E for the communication between mesh nodes as well as for talking to the few devices that are new enough to support it (I like buying cheap second hand devices). 2.5Gbit ethernet connections on all mesh nodes would be good too. Wifi 7 is semi-released, you can buy devices even though the specs aren t entirely finalised. I expect that next year when Wifi 7 devices are more common the second hand prices of Wifi 6E will drop. Currently Wifi 6E devices are somewhat expensive. One major problem at the moment is cloud configuration . Here is a 41 page forum thread of TP-Link customers asking in vain for non-cloud configuration [1]. The problems with cloud configuration are that it doesn t allow configuration without Internet access (so no fixing things when internet breaks and no use for a private network without Internet), it relies on a proprietary phone app (so a problem with your phone breaks everything), and it adds a dependency on an unpaid service that TP-Link might decide to turn off at some future time. The TP -Link Deco X55 AX3000 looks like a good set of devices, it currently costs $328 for a set of three Wifi 6 (not 6E) devices is a good deal, pity that the poor software options let it down. TP-Link also seems to be scanning web traffic and sending the analysis to an external site [2], it seems to be operating as malware. The TP-Link software seems to be most accurately described as malware. There is the OpenWrt project for open firmware on Wifi APs which is a great project [3] but it doesn t seem to support any Wifi 6 mesh systems yet. If most Wifi hardware requires malware for operation it seems that running a VPN over Wifi is the way to go. A hostile party being able to sniff your home network is much worse than a hostile party sniffing public Internet traffic. The Google Nest mesh devices have good specs and price, $359 for a three node Wifi 6E mesh that has 2.5Gbit ethernet. But they can only be configured with a Google app for Android or iOS and require a Gmail account. Giving Google the ability to shut down all my stuff by deleting my gmail account is not acceptable. Also Google is well known for cancelling services [4]. A mitigating factor is that there should be enough of those devices sold to make them a good target for an OpenWRT port. As an aside it looks like the TailScale mesh VPN system could be a solution to the security issues related to malware on Wifi APs problem [5]. There is also HeadScale which is the fully open source variant of that [6]. Even when the vendor isn t overtly hostile they can make mistakes so encryption is good. Kogan is selling an own-brand Wifi 6 mesh network package that comes with 1/2/3 devices for $70/$120/$140. It doesn t do Wifi 6E but supports the better encoding methods of Wifi 6 over Wifi 5 and will be good for bridging a LAN in one part of a house to a Wifi 2.4GHz or Ethernet connected device in another part. They also support up to 7 nodes so you could buy two of the 3 device packages and run one network with 2 and another with 4. The pricing is very competitive and they support web based administration! I ve just ordered the $140 Wifi 6 pack from Kogan. If it doesn t do what I want then I can find someone else who will be happy with whatever functionality it gives and $140 is an amount I can risk without concern. If it works well then I might upgrade to Wifi 6E or Wifi 7 next year and deploy the Wifi 6 one for a relative. It seems that for my needs a cheap and OK Wifi 6 device is better than an expensive Wifi 6E device.
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Russell Coker: Is Secure Boot Worth Using?

With news like this one cited by Bruce Schneier [1] people are asking whether it s worth using Secure Boot. Regarding the specific news article, this is always a risk with distributed public key encryption systems. Lose control of one private key and attackers can do bad things. That doesn t make it bad it just makes it less valuable. If you want to setup a system for a government agency, bank, or other high value target then it s quite reasonable to expect an adversary to purchase systems of the same make and model to verify that their attacks will work. If you want to make your home PC a little harder to attack then you can expect that the likely adversaries won t bother with such things. You don t need security to be perfect, making a particular attack slightly more difficult than other potential attacks gives a large part of the benefit. The purpose of Secure Boot is to verify the boot loader with a public key signature and then have the boot loader verify the kernel. Microsoft signs the shim that is used by each Linux distribution to load GRUB (or another boot loader). So when I configure a Debian system with Secure Boot enabled that doesn t stop anyone from booting Ubuntu. From the signatures on the boot loader etc there is no difference from my Debian installation and a rescue image from Debian, Ubuntu, or another distribution booted by a hostile party to do things against my interests. The difference between the legitimate OS image and malware is a matter of who boots it and the reason for booting it. It is possible to deconfigure Microsoft keys from UEFI to only boot from your own key, this document describes what is necessary to do that [2]. Basically if you boot without using any option ROMs (which among other things means the ROM from your video card) then you can disable the MS keys. If it s impossible to disable the MS keys that doesn t make it impossible to gain a benefit from the Secure Boot process. You can use a block device decryption process that involves a signature of the kernel and the BIOS being used as part of the decryption for the device. So if a system is booted with the wrong kernel and the user doesn t recognise it then they will find that they can t unlock the device with the password. I think it s possible on some systems to run the Secure Boot functionality in a non-enforcing mode such that it will use a bootloader without a valid signature but still use the hash for TPM calculations, that appears impossible on my Thinkpad Yoga Gen3 which only has enabled and disabled as options but should work on Dell laptops which have an option to run Secure Boot in permissive mode. I believe that the way of the future is to use something like EFIStub [3] to create unified kernel images with a signed kernel, initrd, and command-line parameters in a single bundle which can be loaded directly by the UEFI BIOS. From the perspective of a distribution developer it s good to have many people using the current standard functionality of shim and GRUB for EFI as a step towards that goal. CloudFlare has a good blog post about Linux kernel hardening [4]. In that post they cover the benefits of a full secure boot setup (which is difficult at the current time) and the way that secure boot enables the lockdown module for kernel integrity. When Secure Boot is detected by the kernel it automatically enables lockdown=integrity functionality (see this blog post for an explanation of lockdown [5]). It is possible to enable this by putting lockdown=integrity on the kernel command line or lockdown=confidentiality if you want even more protection, but it happens by default with Secure Boot. Secure Boot is something you can set to get a selection of security features enabled and get a known minimum level of integrity even if the signatures aren t used for anything useful, restricting a system to only boot kernels from MS, Debian, Ubuntu, Red Hat, etc is not useful. For most users I think that Secure Boot is a small increase in security but testing it on a large number of systems allows increasing the overall security of operating systems which benefits the world. Also I think that having features like EFIStub usable for a large portion of the users (possibly the majority of users) is something that can be expected to happen in the lifetime of hardware being purchased now. So ensuring that Secure Boot works with GRUB now will facilitate using EFIStub etc in future years. The Secure Boot page on the Debian wiki is worth reading, and also worth updating for people who want to contribute [6].
Related posts:
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22 August 2024

Thomas Goirand: Packaging Home Assistant

During Debconf, Edward Betts and myself started packaging Home Assistant for Debian. It consists of hundreds of Python packages. So far, we counted at least 675 packages. That s a lot, though most packages are just libraries to talk with some IoT devices and some APIs. It s fairly easy to create a new package: it takes me about 15 to 20 minutes, probably half that time to Edward. And it s a lot of fun. So far in one month of time, we managed to package about 1 third of the list (probably 200+ Python packages already). Once we ve done all the dependencies, we may start to have fun with the core of the application! At the current speed, hopefully we ll be done before the end of the year. Edward and myself have swear to make at least one package a day, which I ve been doing so far, and Edward did a way more We also received contributions from Silton0506, Tianyu, piotr, EiPi Fun, sourabhtk37, and Count-Dracula, as per the very bottom of the TODO list in the wiki (see link below). If you have a bit of free time, we d love to have more contributors. Here s were to get the needed information: We created a team in Salsa: https://salsa.debian.org/homeassistant-team/ Our TODO list: https://wiki.debian.org/Python/HomeAssistant Our DDPO Q/A page: https://qa.debian.org/developer.php?login=team%2Bhomeassistant%40tracker.debian.org Feel free to join us on IRC: #debian-homeassistant Discussing with a lot of people about it, I realized that A LOT of DDs are actually using Home Assistant. Wouldn t you like it better if it was just a apt install away ? Any DD can simply take a package in the wiki, open an ITP, upload it s debianized source on Salsa, and upload to the Debian archive. Most are very easy simple packages to make.

Jonathan McDowell: Thoughts on Advent of Code + Rust

Diego wrote about his dislike for Advent of Code and that reminded me I hadn t written up my experience from 2023. Mostly because, spoiler, I never actually completed it and always intended to do so and then write it up. I think it s time to accept I m not going to do that, and write down some thoughts before I forget all of them. These are somewhat vague, given the time that s elapsed, but I think still relevant. You might also find Roger s problem write up interesting. I ve tried AoC a couple of times before; I think I had a very brief attempt back in 2021, and I got 4 days in for 2022. For Advent of Code 2023 I tried much harder to actually complete the challenges, and got most of the way there. I didn t allow myself to move on to the next day until fully completing the previous day, and didn t end up doing the second half of December 24th, or any of December 25th.

Rust First I want to talk about Rust, which is the language I chose to use for the problems. I ve dabbled a little in it, but I d like more familiarity with the basic language, and some programming problems seemed like a good way to get that. It s a language I want to like; I ve spent a lot of my career writing C, do more in Go these days, and generally think Rust promises a low level, run-time light environment like C but with the rough edges taken off. I set myself the challenge of using just bare Rust; no external crates, no use of cargo. I was accused of playing on hard mode by doing this, but it really wasn t the intention - I figured that I should be able to do what I needed without recourse to anything outside the core language, and didn t want what seemed like the extra complexity of dealing with cargo. That caused problems, however. I m used to by-default generic error handling in Go through the error type, but Rust seems to have much more tightly typed errors. I was pointed at anyhow as the right way to do this in Rust. I still find this surprising; I ended up using unwrap() a lot when I think with more generic error handling I could have used ?. The other thing I discovered is that by default rustc is heavy on the debug output. I got significantly better results on some of the solutions with rustc -O -C target-cpu=native source.rs. I probably shouldn t be surprised by this, but worth noting. Rust, to me, has a syntax only a C++ programmer could love. I am not a C++ programmer. Coming from C I found Go to be a nice, simple syntax to learn. Rust has not been the same. There s a lot more punctuation, and it s not always clear to me what it s doing. This applies more when reading other people s code than when writing it myself, obviously, but I see a lot of Rust code that could give Perl a run for its money in terms of looking like line noise. The borrow checker didn t bug me too much, but did add overhead to my thinking. The Rust compiler is generally very good at outputting helpful error messages when the programmer is an idiot. I ended up having to use a RefCell for one solution, and using .iter() for loops rather than explicit iterators (why, why is this different?). I also kept forgetting to explicitly mark variables as mutable when declaring them. Things I liked? There s a rich set of first class data types. Look, I m a C programmer, I m easily pleased. You give me some sort of hash array and I ll be happy. Rust manages that, tuples, strings, all the standard bits any modern language can provide. The whole impl thing for adding methods to structures I like as a way of providing some abstraction, though I think Go has a nicer syntax for it. The compiler, as mentioned, is great at spitting out useful errors for the most part. Also although I wasn t using external crates for AoC I do appreciate there s a decent ecosystem there now (though that brings up another gripe: rust seems to still be a fairly fast moving target, to the extent I can no longer rely on the compiler in Debian stable to be able to compile random projects I find).

Advent of Code Let s talk about the advent of code bit now. Hopefully it s long enough since it came out that this won t be spoilers for anyone, but if you haven t attempted the 2023 AoC and might, you might want to stop reading here. First, a refresher on the format for those who might not be aware of it. Problems are posted daily from December 1st until the 25th. Each is in 2 parts; the second part is not viewable until you have provided the correct answer for the first part. There s a whole leaderboard thing going on, but the puzzle opens at midnight UTC-5 so generally by the time I wake up and have time to look the problem has been solved many times over; no chance of getting listed. Credit to AoC creator, Eric Wastl, for writing up the set of problems in an entertaining fashion. I quite enjoyed seeing how the puzzle would be phrased each day, and the whole thing obviously brings a lot of joy to folk I know. I always start AoC thinking it ll be a fun set of puzzles to solve. Then something happens and I miss a day or two, and all of a sudden I ve a bunch of catching up to do and it s all a bit more of a chore. I hit that at some points this time, but made a concerted effort to try and power through it. That perseverance was required up front, because I found the second part of Day 1 to be ill specified, and had to iterate a few times to actually calculate the desired solution (IIRC, issues about whether sevenone at the end of a line ended up as 7 or 1 really tripped me up). I don t recall any other problems that bit me as hard on the specification as this one, but it happening up front was unfortunate. The short example input doesn t always help with this either; either it s not enough to be able to extrapolate patterns, or it doesn t show all the variations you need to account for (that aren t fully specified in the text), or in a few cases it turned out I needed to understand the shape of the actual data to produce a solution that could actually complete in a reasonable time. Which brings me to another matter, sometimes brute force doesn t actually work. This is fine, but the second part of the day s problem can change the approach you d take. So sometimes I got lucky in the way I handled the first half, and doing the second half was a simple 5 minute tweak, and sometimes I had to entirely change the way I was storing data. You might claim that if I was a better programmer I d have always produced a first half solution that was amenable to extension for the second half. First, I dispute that; I think there are always situations where the problem domain can change in enough directions that you can t handle all of them without a lot of effort. Secondly, I didn t find AoC an environment that encouraged me to optimise for generic solutions. Maybe some of the puzzles in isolation would allow for that, but a month of daily problems to solve while still engaging in regular life meant I hacked things up, took short cuts based on the knowledge I had of the input data, etc, etc. Overall I can see the appeal, but the sheer quantity and the fact I write code as part of my day job just made it feel too much like a chore, rather than a fun mental exercise. I did wonder how they d look as a set of interview puzzles (obviously a subset, rather than all of them), but I m not sure how you d actually use them for that - I wouldn t want anyone to have to solve them in a live interview. So, in case it s not obvious, I m not planning to engage in AoC again this yet. But I m continuing to persevere with Rust (though most of my work stuff is thankfully still Go).

Debian Brasil: Debian Day 2024 em Natal/RN - Brasil

por Allythy O Debian Day um evento anual que celebra o anivers rio do Debian, uma das distribui es GNU/Linux mais importante do Software Livre, criada em 16 de Agosto de 1993, por Ian Murdock. No ltimo s bado (17/08/2024) no Sebrae-RN comemoramos os 31 anos Debian em Natal, no Rio Grande do Norte. A celebra o, foi organizada pela PotiLivre(Comunidade Potiguar de Software Livre), destacou os 31 anos de hist ria do Debian. O evento contou com algumas palestras e muitas discuss es sobre Software Livre. Tivemos 70 inscri es, 40 estiverem presentes. O Debian Day em Natal foi uma ocasi o para celebrar a trajet ria do Debian e refor ar a import ncia do Software Livre. Palestrantes Agradecemos imensamente a Isaque Barbosa Martins, Eduardo de Souza Paix o, Fernando Guisso,que palestraram nessa edi o! Obrigado por compartilhar tanto conhecimento com a comunidade. Esperamos ver voc s novamente em futuros encontros! foto da palestra conhecendo projeto Debian Link dos slides do Debian Day Participantes Um grande obrigado tamb m a todos os participantes, n s fazemos isso por voc s! Esperamos que tenham aprendido, se divertido e feito novas conex es entre a comunidade Participantes do Debian Day Natal-RN Essa edi o do Debina Day Natal foi organizada por: Allythy, Clara Nobre, Gabriel Damazio e Marcel Ribeiro.

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