Before I upload packages to Debian, I always do a full build from source under sbuild. This ensures that the package can build from source on a clean environment, implying that the set of build dependencies is complete. But when iterating on a non-trivial package locally, I will usually build the package directly on my Debian testing system, and I want to take advantage of ccache to cache native (C/C++) code compilation to speed things up. In Debian, the easiest way to enable ccache is to add /usr/lib/ccache to your $PATH. I do this by doing something similar to the following in my ~/.bashrc:

export PATH=/usr/lib/ccache:$PATH

I noticed, however, that my Debian package builds were not using the cache. When building the same small package manually using make, the cache was used, but not when the build was wrapped with dpkg-buildpackage. I tracked it down to the fact that in compatibility level 13+, debhelper will set $HOME to a temporary directory. For what's it worth, I think that's a good thing: you don't want package builds reaching for your home directory as that makes it harder to make builds reproducible, among other things. This behavior, however, breaks ccache. The default cache directory is $HOME/.ccache, but that only gets resolved when ccache is actually used. So we end up starting with an empty cache on each build, get a 100% cache miss rate, and still pay for the overhead of populating the cache. The fix is to explicitly set $CCACHE_DIR upfront, so that by the time $HOME gets overriden, it doesn't matter anymore for ccache. I did this in my ~/.bashrc:

export CCACHE_DIR=$HOME/.ccache

This way, $HOME will be expanded right there when the shell starts, and by the time ccache is called, it will use the persistent cache in my home directory even though $HOME will, at that point, refer to a temporary directory.

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.

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!

Google docs has some tab feature. I received a note that my script addTodayDate may need to be modified to handle the feature. tabs API. But then I don't think I need it yet, so I will just use the default tab.

Another (again somewhat minor) maintenance release of the RcppCNPy package arrived on CRAN earlier today. RcppCNPy provides R with read and write access to NumPy files thanks to the cnpy library by Carl Rogers along with Rcpp for the glue to R. A change in the most recent Rcpp appears to cause void functions wrapper via Rcpp Modules to return NULL, as opposed to being silent. That tickles discrepancy between the current output and the saved (reference) output of one test file, leading CRAN to display a NOTE which we were asked to take care of. Done here in this release and now that we know we will also look into restoring the prior Rcpp behaviour. Other small changes involved standard maintenance for continuous integration and updates to files README.md and DESCRIPTION. More details are below.

Changes in version 0.2.13 (2024-09-03)

• A test script was updated to account for the fact that it now returns a few instances of NULL under current Rcpp.
• Small package maintenance updates have been made to the README and DESCRIPTION files as well as to the continuous integration setup.

CRANberries also provides a diffstat report for the latest release. As always, feedback is welcome and the best place to start a discussion may be the GitHub issue tickets page. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

tl;dr DebConf24 was fun! A playlist of all of my talks, with subtitles (en, pt-br) and chapters is available on YouTube.

Overview DebConf24 was held in Busan, South Korea, between Sunday July 28th to Sunday August 4th 2024. As usual for DebConfs, I had a great time meeting my friends, but also met new people and got to learn a bit about the interesting things they're working on. I ended up getting too excited during the talk submission stage of the conference and as a result I presented 5 different activities (3 talks, 1 BoF and 1 lightning talk). Since I was too busy with the presentations, I did not have a lot of time to actually hang out with folks, or even to go out in the city, I guess I've learned my lesson for next time. The main purpose of this post is to write about all of the things I presented at the conference. I did want to list some of the interesting talks I've watched, but that I would not be able to be fair as I'm sure I would miss some. You can get the schedule and the recordings of any talks from the conference's website: https://debconf24.debconf.org/schedule/

wcurl Lightning Talk The most fun of my presentations, during the second-to-last day of the conference, I've asked for help from Sergio Durigan Junior <sergiodj> to setup an URL containing a whitespace and redirecting that to wcurl's manpage. I then did a little demo to showcase why me (and a lot others) struggle with downloading things with curl, and how wcurl solves that. https://www.youtube.com/watch?v=eM8M5qa4pPM

Fixing CVEs on Debian: Everything you probably know already I've always felt like DebConf was missing security-related talks, so I decided to do something about it and presented a few of the things I've learned when fixing CVEs for Debian. This is an area where we don't get a lot of new contributors, I'm trying to change that, and this talk can be used to introduce newcomers to it. https://www.youtube.com/watch?v=XzNVVILVyUM

The secret sauce of Debian Debian is not very vocal about all of the nice things it has regarding quality-assurance, testing, or CI, even though it's at the state-of-the-art for a lot of things. This talk is an initial step towards making people aware of the cool things happening behind the scenes. Ideally we should have it well-documented somewhere. https://www.youtube.com/watch?v=x_X2IBnpjic

"I use Debian BTW": fzf, tmux, zoxide and friends One of my earliest good memories of Debian was when it started coming with a colored PS1 by default, I still remember the feeling of relief whenever I jumped into a Debian server and didn't have to deal with a black and white PS1. There's still a lot of room for Debian to ship better defaults, and I think some of them can actually happen. This talk is a bit of a silly one where I'm just making people aware of the existence of a few Golang/Rust CLI tools, and also some dotfiles configurations that should probably be the default. https://www.youtube.com/watch?v=tfto3Seokn4

curl The curl project does such a great job with their security advisories that it will likely never receive the amount of praise it deserves, but I did my best at mentioning it throughout my CVEs talk. Maybe I will write more extensively about this someday, but in case I don't:

---

There's no other project which always consistently mentions the exact range of commits that are affected by a given CVE. Forget about whether the versions are EOL, curl doesn't have LTS releases, yet they do such a great job at clearly documenting their CVEs that I would take that over having LTS releases anytime (that's for curl at least, I acknowledge some types of projects have a different need for LTS releases). Not only that, but they are also always careful about explaining alternative mitigations such as configuration changes, build flags that defuse the exploitation, or parameters that you should not use.

---

Just like we tend to do every time we meet, me and the other Debian curl maintainers spent the first 2 or 3 days of the conference talking about how we wanted to eventually meet up to discuss the package. It was going to be informal, maybe during the Cheese and Wine party, but then I've realized we should make it part of the official schedule, which would also give us the recordings for later. And so the "curl maintainers BoF" happened, where we spoke about HTTP3, GnutTLS, wcurl and other things. https://www.youtube.com/watch?v=fL7hSypUTdM

wcurl Right after that BoF, Daniel Stenberg asked if we were interested in having wcurl adopted into curl, which we definitely were, so wcurl is now part of the curl project. Daniel was also kind enough to design a logo for the project, which makes me especially happy because I can stop with my own approach at a logo (which I had to redo every few days): And here is the new logo: Much better, I would say :)

curl Swag DebConf24 was my chance at forwarding some curl swag items to the other curl maintainers, so both Sergio Durigan Junior <sergiodj> and Carlos Henrique Lima Melara <charles> got the curl-up t-shirt and the very cool curl PCB coaster, both gifted by Daniel Stenberg. Unfortunately I didn't have any of that for DebConf attendees, but I did drop loads of curl stickers at the stickers table, they were gone very quickly.

For the future I used to think the most humbling experience you could have as someone who presented a talk was to have to watch it yourself, you notice a lot of mistakes and you instantly think about things that should be done differently. It turns out the most humbling thing to do is actually to write subtitles for your talks, I noticed every single mistake, often multiple times. So after spending more than 30 hours writing the subtitles for both English and Brazilian Portuguese for my talks, I feel like it's going to be much easier to avoid committing the same mistakes again. After some time you stop feeling shame about those mistakes and you're just left with feelings of annoyance, and at that point it becomes easier to consciously avoid them. I am collecting a list of things I wish I had done differently on all of those talks, so if I end up presenting any one of them again, it will be an improved version.

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 #debian-localgroups on the OFTC IRC network, also plumbed on Matrix at #debian-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!

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.

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

Review: The Shepherd's Crown, by Terry Pratchett

Series:	Discworld #41
Publisher:	Harper
Copyright:	2015
Printing:	2016
ISBN:	0-06-242998-1
Format:	Trade paperback
Pages:	276

The Shepherd's Crown is the 41st and final Discworld novel and the 5th and final Tiffany Aching novel. You should not start here. There is a pretty major character event in the second chapter of this book. I'm not going to say directly what it is, but you will likely be able to guess from the rest of the review. If you're particularly adverse to spoilers, you may want to skip reading this until you've read the book. Tiffany Aching is extremely busy. Witches are responsible for all the little tasks that fall between the cracks, and there are a lot of cracks. The better she gets at her job, the more of the job there seems to be.

"Well," said Tiffany, "there's too much to be done and not enough people to do it." The smile that the kelda gave her was a strange one. The little woman said, "Do ye let them try? Ye mustn't be afraid to ask for help. Pride is a good thing, my girl, but it will kill you in time."

And that's before an earth-shattering change in the world of witches, one that leaves Tiffany shuttling between Lancre and the Chalk trying to be too many things to too many people. Plus the kelda is worried some deeper trouble is brewing. And then Tiffany gets an exiled elven queen who has never understood the worth of other people dumped on her, and has to figure out what to do with her. The starting idea is great. I continue to be impressed with how well Pratchett handles Tiffany's coming-of-age story. Finding one's place in the world isn't one lesson or event; it's layers of them, with each new growth in responsibility uncovering new things to learn that are often quite different from the previous problems. Tiffany has worked through child problems, adolescent problems, and new adulthood problems. Now she's on a course towards burnout, which is exactly the kind of problem Tiffany would have given her personality. Even better, the writing at the start of The Shepherd's Crown is tight and controlled and sounds like Pratchett, which was a relief after the mess of Raising Steam. The contrast is so sharp that I found myself wondering if parts of this book had been written earlier, or if Pratchett found a new writing or editing method. The characters all sound like themselves, and although some of the turns of phrase are not quite as sharp as in earlier books, they're at least at the level of Snuff. Unfortunately, it doesn't last. There are some great moments and some good quotes, but the writing starts to slip at about the two-thirds point, the sentences began to meander, the characters start repeating the name of the person they're talking to, and the narration becomes increasingly strained. It felt like Pratchett knew the emotional tone he wanted to evoke but couldn't find a subtle way to express it, so the story and the characters start to bludgeon the reader with Grand Statements. It's never as bad as Raising Steam, but it doesn't slip smoothly off the page to rewrite your brain the way that Pratchett could at his best. What makes this worse is that the plot is not very interesting. I wanted to read a book about Tiffany understanding burnout, asking for help, and possibly also about mental load and how difficult delegation is. There is some movement in that direction: she takes on some apprentices, although we don't see as much of her interactions with them as I'd like, and there's an intriguing new male character who wants to be a witch. I wish Pratchett had been able to give Geoffrey his own book. He and his goat were the best part of the story, but it felt rushed and I think he would have had more impact if the reader got to see him develop his skills over time the way that we did with Tiffany. But, alas, all of that is side story to the main plot, which is about elves. As you may know from previous reviews, I do not get along with Pratchett's conception of elves. I find them boring and too obviously evil, and have since Lords and Ladies. Villains have never been one of Pratchett's strengths, and I think his elves are my least favorite. One of the goals of this book is to try to make them less one-note by having Tiffany try to teach one of them empathy, but I didn't find any of the queen's story arc convincing. If Pratchett had pulled those threads together with something more subtle, emotional, and subversive, I think it could have worked, but instead we got another battle royale, and Lords and Ladies did that better.

"Granny never said as she was better than others. She just got on with it and showed 'em and people worked it out for themselves."

And so we come to the end. I wish I could say that the quality held up through the whole series, and it nearly did, but alas it fell apart a bit at the end. Raising Steam I would skip entirely. The Shepherd's Crown is not that bad, but it's minor Pratchett that's worth reading mainly because it's the send-off (and there are a lot of reasons within the story to think Pratchett knew that when writing it). There are a few great lines, some catharsis, and a pretty solid ending for Tiffany, but it's probably not a book that I'll re-read. Content warning: major character death. Special thanks to Emmet Asher-Perrin, whose Tor.com/Reactor re-read of all of Discworld got me to pick the series up again and finally commit to reading all of it. I'm very glad I did. Rating: 6 out of 10

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

Warning: If you're not into meat, you might want to skip the rest of this... This year, I turned 50. Wow. Lots of friends and family turned up to help me celebrate, with a BBQ (of course!). I was very grateful for a lovely set of gifts from those awesome people, and I have a number of driving experiences to book in the next year or so. I'm going to have so much fun driving silly cars on and off road! However, the most surprising gift was something totally different - a full-day course of hands-on pork butchery. I was utterly bemused - I've never considered doing anything like this at all, and I'd certainly never talked to friends about anything like it either. I was shocked, but in a good way! So, two weekends back Jo and I went over to Empire Farm in Somerset. We stayed nearby so we could be ready on-site early on Sunday morning, and then we joined three other people doing the course. Jo was there to observe, i.e. to watch and take (lots of!) pictures. I can genuinely say that this was the most fun surprise gift I've ever received! David Coldman, the master butcher working with us, has been in the industry for many years. He was an excellent teacher, showing us everything we needed to know and being very patient with us when we needed it. It was great to hear his philosophy too - he only uses the very best locally-sourced meat and focuses on quality over quantity. He showed us all the different cuts of pork that a butcher will make, and we were encouraged to take everything home - no waste here! At the beginning of the day, we each started with half a pig. Over the next several hours, we steadily worked our way through a series of cuts with knife and saw, making the remaining pig smaller and smaller as we went. We finished the day with three sets of meat. First, a stack of vacuum-packed joints, chops and steaks ready for cooking and eating at home. Second: a box of off-cuts that we minced and made into sausages at the end of the day. Finally: a bag of skin and bones. Our friend's dog got some of the bones, and Jo turned a lot of the skin into crackling that we shared with friends at the OMGWTFBBQ the next weekend. This was an amazing day. Massive thanks to my good friend Chris Walker for suggesting this gift. As I told David on the day: this was the most fun surprise gift I've ever received. Good hands-on teaching in a new craft is an incredible thing to experience, and I can't recommend this course highly enough.

Around a decade ago, I was happy to learn about bcache a Linux block cache system that implements tiered storage (like a pool of hard disks with SSDs for cache) on Linux. At that stage, ZFS on Linux was nowhere close to where it is today, so any progress on gaining more ZFS features in general Linux systems was very welcome. These days we care a bit less about tiered storage, since any cost benefit in using anything else than nvme tends to quickly evaporate compared to time you eventually lose on it. In 2015, it was announced that bcache would grow into its own filesystem. This was particularly exciting and it caused quite a buzz in the Linux community, because it brought along with it more features that compare with ZFS (and also btrfs), including built-in compression, built-in encryption, check-summing and RAID implementations. Unlike ZFS, it didn t have a dkms module, so if you wanted to test bcachefs back then, you d have to pull the entire upstream bcachefs kernel source tree and compile it. Not ideal, but for a promise of a new, shiny, full-featured filesystem, it was worth it. In 2019, it seemed that the time has come for bcachefs to be merged into Linux, so I thought that it s about time we have the userspace tools (bcachefs-tools) packaged in Debian. Even if the Debian kernel wouldn t have it yet by the time the bullseye (Debian 11) release happened, it might still have been useful for a future backported kernel or users who roll their own. By total coincidence, the first git snapshot that I got into Debian (version 0.1+git20190829.aa2a42b) was committed exactly 5 years ago today. It was quite easy to package it, since it was written in C and shipped with a makefile that just worked, and it made it past NEW into unstable in 19 January 2020, just as I was about to head off to FOSDEM as the pandemic started, but that s of course a whole other story. Fast-forwarding towards the end of 2023, version 1.2 shipped with some utilities written in Rust, this caused a little delay, since I wasn t at all familiar with Rust packaging yet, so I shipped an update that didn t yet include those utilities, and saw this as an opportunity to learn more about how the Rust eco-system worked and Rust in Debian. So, back in April the Rust dependencies for bcachefs-tools in Debian didn t at all match the build requirements. I got some help from the Rust team who says that the common practice is to relax the dependencies of Rust software so that it builds in Debian. So errno, which needed the exact version 0.2, was relaxed so that it could build with version 0.4 in Debian, udev 0.7 was relaxed for 0.8 in Debian, memoffset from 0.8.5 to 0.6.5, paste from 1.0.11 to 1.08 and bindgen from 0.69.9 to 0.66. I found this a bit disturbing, but it seems that some Rust people have lots of confidence that if something builds, it will run fine. And at least it did build, and the resulting binaries did work, although I m personally still not very comfortable or confident about this approach (perhaps that might change as I learn more about Rust). With that in mind, at this point you may wonder how any distribution could sanely package this. The problem is that they can t. Fedora and other distributions with stable releases take a similar approach to what we ve done in Debian, while distributions with much more relaxed policies (like Arch) include all the dependencies as they are vendored upstream. As it stands now, bcachefs-tools is impossible to maintain in Debian stable. While my primary concerns when packaging, are for Debian unstable and the next stable release, I also keep in mind people who have to support these packages long after I stopped caring about them (like Freexian who does LTS support for Debian or Canonical who has long-term Ubuntu support, and probably other organisations that I ve never even heard of yet). And of course, if bcachfs-tools don t have any usable stable releases, it doesn t have any LTS releases either, so anyone who needs to support bcachefs-tools long-term has to carry the support burden on their own, and if they bundle it s dependencies, then those as well. I ll admit that I don t have any solution for fixing this. I suppose if I were upstream I might look into the possibility of at least supporting a larger range of recent dependencies (usually easy enough if you don t hop onto the newest features right away) so that distributions with stable releases only need to concern themselves with providing some minimum recent versions, but even if that could work, the upstream author is 100% against any solution other than vendoring all its dependencies with the utility and insisting that it must only be built using these bundled dependencies. I ve made 6 uploads for this package so far this year, but still I constantly get complaints that it s out of date and that it s ancient. If a piece of software is considered so old that it s useless by the time it s been published for two or three months, then there s no way it can survive even a usual stable release cycle, nevermind any kind of long-term support. With this in mind (not even considering some hostile emails that I recently received from the upstream developer or his public rants on lkml and reddit), I decided to remove bcachefs-tools from Debian completely. Although after discussing this with another DD, I was convinced to orphan it instead, which I have now done. I made an upload to experimental so that it s still available if someone wants to work on it (without having to go through NEW again), it s been removed from unstable so that it doesn t migrate to testing, and the ancient (especially by bcachefs-tools standards) versions that are in stable and oldstable will be removed too, since they are very likely to cause damage with any recent kernel versions that support bcachefs. And so, my adventure with bcachefs-tools comes to an end. I d advise that if you consider using bcachefs for any kind of production use in the near future, you first consider how supportable it is long-term, and whether there s really anyone at all that is succeeding in providing stable support for it.

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.

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

At this years Debian conference in South Korea I've presented1 the new feature of the FAIme web service. You can now build your own Debian live media/ISO. The web interface provides various settings, for e.g. adding a user name and its password, selecting the Debian release (stable or testing), the desktop environment and the language. Additionally you can add your own list of packages, that will be installed into the live environment. It's possible to define a custom script that gets executed during the boot process. For remote access to the live system, you can easily sepcify a github, gitlab or salsa account, whose public ssh key will be used for passwordless root access. If your hardware needs special grub settings, you may also add those. I'm thinking about adding an autologin checkbox, so the live media could be used for a kiosk system. And finally newer hardware is supported with the help of the backports kernel for the Debian stable release (aka bookworm). This combination is not available from the official Debian live images or the netinst media because the later has some complicated dependencies which are not that easy to resolve2. At DebConf24 I've talked to Alper who has some ideas3 how to improve the Debian installer environment which then may support a backports kernel. The FAI web service for live ISO is available at https://fai-project.org/FAIme/live

GNOME is one of the most widely used free and open-source desktop environments! Your native language is Marathi and you are using GNOME as your desktop environment? Then me as the coordinator for the Marathi translation team in GNOME is excited to invite you to become part of the team who is working on translating the GNOME Desktop into Marathi! By this and contributing to the translation of GNOME into Marathi you would be a member of an important project and you can help to make it more accessible to Marathi speakers worldwide and help also to keep our language alive in the open source world.

Why Should You Contribute?

• Promote Your Language By translating GNOME into Marathi, you help to preserve and promote our beautiful language in the digital world.
• Learn and Grow Contributing to open-source projects like GNOME is a great way to improve your language and technical skills, network with like-minded individuals, and gain recognition in the global open-source community.
• Give Back to the Community This is an opportunity to contribute to a project that has a significant impact on users around the world. Your work will enable Marathi speakers to use technology in their native language.

Who Can Contribute? You don t need to be a professional translator to join us! If you are fluent in Marathi and have a basic understanding of English, your contributions will be invaluable. Whether you re a student, a professional, or just someone passionate about your language, your help is needed and really appreciated!

How To Start Translating? Once you re familiar with the tools, you can easily begin translating. We have a list of untranslated strings waiting for your contribution!

How To Join The Team? Follow these steps to join the Marathi translation team for GNOME and start contributing:

• Step 1: Visit our GNOME Translation Team Page.
• Step 2: If you re a new user, click on the Create Account option to sign up.
• Step 3: Once you ve created your account, log in with your credentials.
• Step 4: After logging in, click the Join button to become a translator for the Marathi team.
• Step 5: You ll now see a list of different modules that need translation. Choose one of the files that interests you and download it to your computer.
• Step 6: Translate the content locally on your computer. Once you re done, return to the website, click Browse, and submit your translated file.

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Get Familiar with the Additional Tools

Varnam If you re not used to typing in Marathi, you can still contribute using the Varnam website, a free and open-source tool that converts English text into Marathi. Here s how you can get started:

• Step 1: Visit the Varnam website.
• Step 2: Click on the Try Now button on the website.
• Step 3: In the language selection menu, choose Marathi as your desired language.
• Step 4: Now you can start typing in English, and Varnam will automatically convert your text into Marathi. If you need more guidance, there s a help window available on the site that you can explore for additional support.

Need Help Or You Have Questions? If you have any doubts or need further assistance how you get started with translating GNOME into Marathi, don t hesitate to reach out. I m here to help you on every step of the way! You can connect with me directly at kalyaniknkr@gmail.com Whether you need technical support, guidance on using the tools, or just want to discuss the project, feel free to get in touch. Let s work together to make GNOME accessible to Marathi speakers around the world. Your contributions are always invaluable, and I look forward to welcoming you to our team! Thank you for your interest and support!

It's clear that Twitter has been circling the drain for years, but things have been especially bad in recent times. I haven't quit (I have some sympathy with the viewpoint don't cede territory to fascists) but I try to read it much less, and I certainly post much less. Especially at the moment, I really appreciate distractions. Last time I wrote about Mastodon (by which I meant the Fediverse¹), I was looking for a new instance to try. I settled on Debian's social instance². I'm now trying to put any energy I might spend engaging on Twitter, into engaging in the Fediverse instead. (You can follow me via the handle @jon@dow.land, I think, which should repoint to my actual handle, @jmtd@pleroma.debian.social.) There are other potential successors to Twitter: two big ones are Bluesky and Facebook-owned Threads. They are effectively cookie-cutter copies of the Twitter model, and so, we will repeat the same mistakes there. Sadly I see the majority of communities and sub-cultures I follow are migrating to one or the other of these. The Fediverse (or the Mastodon-ish bits of it) should avoid the fate of Twitter. JWZ puts it better and more succinctly than I can. The Fedi experience is, sadly, pretty clunky. So I want to try and write a bit from time to time with tips and tricks that might improve people's experiences. First up, something I discovered only today about Mastodon instances. As JWZ noted, If you are worried about picking the "right" Mastodon instance, don't. Just spin the wheel.. You can spend too much time trying to guess a good answer to this. Better to just get started. At the same time, individual instances are supposed to cater to specific niches. So it could be useful to sample the public posts from an entire instance. For example, to find people to follow, or decide to hop over to that instance yourself. You can't (I think) follow an entire instance from within yours, but, they usually have a public page which shows you the latest traffic. For example, the infosec-themed instance infosec.exchange has one here: https://infosec.exchange/public/local These pages don't provide RSS or Atom feeds³, sadly. I hope that's on the software's roadmap, and hasn't been spurned for ideological reasons. For now at least, OpenRSS provide RSS/Atom feeds for many Mastodon instances. For example, an RSS/Atom feed of the above: https://openrss.org/infosec.exchange/public/local One can add these feeds to your Feed reader and over time get a flavour for the kind of discourse that takes place on given instances. I think the OpenRSS have to manually add Mastodon instances to their service. I tried three instances and only one (infosec.exchange) worked. I'm not sure but I think trying an instance that doesn't work automatically puts it on OpenRSS's backlog.

A new maintenance release of RcppEigen is now on CRAN, and will go to Debian shortly as usual. Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms. RcppEigen is used by 460 other CRAN packages, and has been downloaded 31.9 million times just off the mirrors of CRAN keeping logs for counting. The recent change switing to Authors@R (now that CRAN mandates it) contained in dual typo in ORCID tags, this releases fixes it. The complete NEWS file entry follows.

Changes in RcppEigen version 0.3.4.0.2 (2024-08-23)

• Correct two typos in the ORCID tag

Courtesy of CRANberries, there is also a diffstat report for the most recent release. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

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.

• [1] https://community.tp-link.com/en/home/forum/topic/531350
• [2] https://tinyurl.com/y84skkdp
• [3] https://openwrt.org/supported_devices
• [4] https://killedbygoogle.com/
• [5] https://en.wikipedia.org/wiki/Tailscale
• [6] https://headscale.net/