Search Results: "marv"

6 July 2022

Russ Allbery: Review: A Master of Djinn

Review: A Master of Djinn, by P. Dj l Clark
Series: Dead Djinn Universe #1
Publisher: Tordotcom
Copyright: 2021
ISBN: 1-250-26767-6
Format: Kindle
Pages: 391
A Master of Djinn is the first novel in the Dead Djinn Universe, but (as you might guess from the series title) is a direct sequel to the novelette "A Dead Djinn in Cairo". The novelette is not as good as the novel, but I recommend reading it first for the character introductions and some plot elements that carry over. Reading The Haunting of Tram Car 015 first is entirely optional. In 1912 in a mansion in Giza, a secret society of (mostly) British men is meeting. The Hermetic Brotherhood of Al-Jahiz is devoted to unlocking the mysteries of the Soudanese mystic al-Jahiz. In our world, these men would likely be colonialist plunderers. In this world, they still aspire to that role, but they're playing catch-up. Al-Jahiz bored into the Kaf, releasing djinn and magic into the world and making Egypt a world power in its own right. Now, its cities are full of clockwork marvels, djinn walk the streets as citizens, and British rule has been ejected from India and Africa by local magic. This group of still-rich romantics and crackpots hopes to discover the knowledge lost when al-Jahiz disappeared. They have not had much success. This will not save their lives. Fatma el-Sha'arawi is a special investigator for the Ministry of Alchemy, Enchantments, and Supernatural Entities. Her job is sorting out the problems caused by this new magic, such as a couple of young thieves with a bottle full of sleeping djinn whose angry reaction to being unexpectedly woken has very little to do with wishes. She is one of the few female investigators in a ministry that is slowly modernizing with the rest of society (Egyptian women just got the vote). She's also the one called to investigate the murder of a secret society of British men and a couple of Cairenes by a black-robed man in a golden mask. The black-robed man claims to be al-Jahiz returned, and proves to be terrifyingly adept at manipulating crowds and sparking popular dissent. Fatma and the Ministry's first attempt to handle him is a poorly-judged confrontation stymied by hostile crowds, the man's duplicating bodyguard, and his own fighting ability. From there, it's a race between Fatma's pursuit of linear clues and the black-robed man's efforts to destabilize society. This, like the previous short stories, is a police procedural, but it has considerably more room to breathe at novel length. That serves it well, since as with "A Dead Djinn in Cairo" the procedural part is a linear, reactive vehicle for plot exposition. I was more invested in Fatma's relationships with the supporting characters. Since the previous story, she's struck up a romance with Siti, a highly competent follower of the old Egyptian gods (Hathor in particular) and my favorite character in the book. She's also been assigned a new partner, Hadia, a new graduate and another female agent. The slow defeat of Fatma's irritation at not being allowed to work alone by Hadia's cheerful competence and persistence (and willingness to do paperwork) adds a lot to the characterization. The setting felt a bit less atmospheric than The Haunting of Tram Car 015, but we get more details of international politics, and they're a delight. Clark takes obvious (and warranted) glee in showing how the reintroduction of magic has shifted the balance of power away from the colonial empires. Cairo is a bustling steampunk metropolis and capital of a world power, welcoming envoys from West African kingdoms alongside the (still racist and obnoxious but now much less powerful) British and other Europeans. European countries were forced to search their own mythology for possible sources of magic power, which leads to the hilarious scene of the German Kaiser carrying a sleepy goblin on his shoulder to monitor his diplomacy. The magic of the story was less successful for me, although still enjoyable. The angels from "A Dead Djinn in Cairo" make another appearance and again felt like the freshest bit of world-building, but we don't find out much more about them. I liked the djinn and their widely-varied types and magic, but apart from them and a few glimpses of Egypt's older gods, that was the extent of the underlying structure. There is a significant magical artifact, but the characters are essentially handed an instruction manual, use it according to its instructions, and it then does what it was documented to do. It was a bit unsatisfying. I'm the type of fantasy reader who always wants to read the sourcebook for the magic system, but this is not that sort of a book. Instead, it's the kind of book where the investigator steadily follows a linear trail of clues and leads until they reach the final confrontation. Here, the confrontation felt remarkably like cut scenes from a Japanese RPG: sudden vast changes in scale, clockwork constructs, massive monsters, villains standing on mobile platforms, and surprise combat reversals. I could almost hear the fight music and see the dialog boxes pop up. This isn't exactly a complaint I love Japanese RPGs but it did add to the feeling that the plot was on rails and didn't require many decisions from the protagonist. Clark also relies on an overused plot cliche in the climactic battle, which was a minor disappointment. A Master of Djinn won the Nebula for best 2021 novel, I suspect largely on the basis of its setting and refreshingly non-European magical system. I don't entirely agree; the writing is still a bit clunky, with unnecessary sentences and stock phrases showing up here and there, and I think it suffers from the typical deficiencies of SFF writers writing mysteries or police procedurals without the plot sophistication normally found in that genre. But this is good stuff for a first novel, with fun supporting characters (loved the librarian) and some great world-building. I would happily read more in this universe. Rating: 7 out of 10

24 February 2022

Dirk Eddelbuettel: #36: pub/sub for live market monitoring with R and Redis

Welcome to the 36th post of the really randomly reverberating R, or R4 for short, write-ups. Today s post is about using Redis, and especially RcppRedis, for live or (near) real-time monitoring with R. market monitor There is an saying that you can take the boy out of the valley, but you cannot the valley out of the boy so for those of us who spent a decade or two in finance and on trading floors, having some market price information available becomes second nature. And/or sometimes it is just good fun to program this. A good while back Josh posted a gist on a simple-yet-robust while loop. It (very cleverly) uses his quantmod package to access the SP500 in real-time . (I use quotes here because at the end of retail broadband one is not at the same market action as someone co-located in a New Jersey data center. It is however not delayed: as an index, it is not immediately tradeable as a stock, etf, or derivative may be all of which are only disseminated as delayed price information, usually by ten minutes.) I quite enjoyed the gist and used it and started tinkering with it. For example, it collects data but only saves (i.e. persists ) it after market close. If for whatever reason one needs to restart recent history is gone. In any event, I used his code and generalized it a little and published this about a year ago as function intradayMarketMonitor() in my dang package. (See this blog post announcing it.) The chart of the left shows this in action, the chart is a snapshot from a couple of days ago when the vignettes (more on them below) were written. As lovely as intradayMarketMonitor() is, it also limits itself to market hours. And sometimes you want to see, say, how the market opens on Sunday (futures usually restart at 17h Chicago time), or how news dissipates during the night, or where markets are pre-open, or . So I both wanted to complement this with futures, and also cache it locally so that, say, one machine might collect data and one (or several others) can visualize. For such tasks, Redis is unparalleled. (Yet I also always felt Redis could do with another, simple, short and sweet introduction stressing the key features of i) being multi-lingual: write in one language, consume in another and ii) loose coupling: no linking as one talks to Redis via standard tcp/ip networking. So I wrote a new intro vignette that is now in RcppRedis. I hope this comes in handy. Comments welcome!) Our RcppRedis package had long been used for such tasks, and it was easy to set it up. Standard use is to loop, fetch some data, push it to Redis, sleep, and start over. Clients do the same: fetch most recent data, plot or report it, sleep, start over. That works, but it has a dual delay as the client sleeping may miss the data update! The standard answer to this is called publish/pubscribe, or pub/sub. Libraries such as 0mq or zeromq specialise in this. But it turns out Redis already has it. I had some initial difficulty adding it to RcppRedis so for a trial I tested the marvellous rredis package by Bryan and simply instantiated two Redis clients. Now the data getter simply publishes a new data point in a given channel, by convention named after the security it tracks. Clients register with the Redis server which does all the actual work of keeping track of who listens to what. The clients now simply listen (which is a blocking operation) and as soon as data comes in receive it. market monitor This is quite mesmerizing when you just run two command-line clients (in a byobu session, say). As sone as the data is written (as shown on console log) it is consumed. No measruable overhead. Just lovely. Bryan and I then talked a litte as he may or may not retire rredis. Having implemented the pub/sub logic for both sides once, he took a good hard look at RcppRedis and just like that added it there. With some really clever wrinkles for (optional) per-symbol callback as closure attached to the instance. Truly amazeballs And once we had it in there, generalizing from publishing or subscribing to just one symbol easily generalizes to having one listener collect and publish for multiple symbols, and having one or more clients subscribe and listen one, more or even all symbol. All with ease thanks tp Redis. The second chart, also from a few days ago, shows four symbols for four (front-contract) futures for Bitcoin, Crude Oil, SP500, and Gold. As all this can get a little technical, I wrote a second vignette for RcppRedis on just this: market monitoring. Give this a read, if interested, feedback on this one is most welcome too! But all the code you need is included in the package just run a local Redis instance. Before closing, one sour note. I uploaded all this in a new and much improved updated RcppRedis 0.2.0 to CRAN on March 13 ten days ago. Not only is it still not there , but CRAN in their most delightful way also refuses to answer any emails of mine. Just lovely. The package exhibited just one compiler warning: a C++ compiler objected to the (embedded) C library hiredis (included as a fallback) for using a C language construct. Yes. A C++ compiler complaining about C. It s a non-issue. Yet it s been ten days and we still have nothing. So irritating and demotivating. Anyway, you can get the package off its GitHub repo. 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.

21 November 2021

Antoine Beaupr : The last syncmaildir crash

My syncmaildir (SMD) setup failed me one too many times (previously, previously). In an attempt to migrate to an alternative mail synchronization tool, I looked into using my IMAP server again, and found out my mail spool was in a pretty bad shape. I'm comparing mbsync and offlineimap in the next post but this post talks about how I recovered the mail spool so that tools like those could correctly synchronise the mail spool again.

The latest crash On Monday, SMD just started failing with this error:
nov 15 16:12:19 angela systemd[2305]: Starting pull emails with syncmaildir...
nov 15 16:12:22 angela systemd[2305]: smd-pull.service: Succeeded.
nov 15 16:12:22 angela systemd[2305]: Finished pull emails with syncmaildir.
nov 15 16:14:08 angela systemd[2305]: Starting pull emails with syncmaildir...
nov 15 16:14:11 angela systemd[2305]: smd-pull.service: Main process exited, code=exited, status=1/FAILURE
nov 15 16:14:11 angela systemd[2305]: smd-pull.service: Failed with result 'exit-code'.
nov 15 16:14:11 angela systemd[2305]: Failed to start pull emails with syncmaildir.
nov 15 16:16:14 angela systemd[2305]: Starting pull emails with syncmaildir...
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: Network error.
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: Unable to get any data from the other endpoint.
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: This problem may be transient, please retry.
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: Hint: did you correctly setup the SERVERNAME variable
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: on your client? Did you add an entry for it in your ssh
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: configuration file?
nov 15 16:16:17 angela smd-pull[27178]: smd-client: ERROR: Network error
nov 15 16:16:17 angela smd-pull[27188]: register: smd-client@localhost: TAGS: error::context(handshake) probable-cause(network) human-intervention(avoidable) suggested-actions(retry)
nov 15 16:16:17 angela systemd[2305]: smd-pull.service: Main process exited, code=exited, status=1/FAILURE
nov 15 16:16:17 angela systemd[2305]: smd-pull.service: Failed with result 'exit-code'.
nov 15 16:16:17 angela systemd[2305]: Failed to start pull emails with syncmaildir.
What is frustrating is that there's actually no network error here. Running the command by hand I did see a different message, but now I have lost it in my backlog. It had something to do with a filename being too long, and I gave up debugging after a while. This happened suddenly too, which added to the confusion. In a fit of rage I started this blog post and experimenting with alternatives, which led me down a lot of rabbit holes. Reviewing my previous mail crash documentation, it seems most solutions involve talking to an IMAP server, so I figured I would just do that. Wanting to try something new, i gave isync (AKA mbsync) a try. Oh dear, I did not expect how much trouble just talking to my IMAP server would be, which wasn't not isync's fault, for what that's worth. It was the primary tool I used to debug things, and served me well in that regard.

Mailbox corruption The first thing I found out is that certain messages in the IMAP spool were corrupted. mbsync would stop on a FETCH command and Dovecot would give me those errors on the server side.

"wrong W value"
nov 16 15:31:27 marcos dovecot[3621800]: imap(anarcat)<3630489><wAmSzO3QZtfAqAB1>: Error: Mailbox junk: Maildir filename has wrong W value, renamed the file from /home/anarcat/Maildir/.junk/cur/1454623938.M101164P22216.marcos,S=2495,W=2578:2,S to /home/anarcat/Maildir/.junk/cur/1454623938.M101164P22216.marcos,S=2495:2,S
nov 16 15:31:27 marcos dovecot[3621800]: imap(anarcat)<3630489><wAmSzO3QZtfAqAB1>: Error: Mailbox junk: Deleting corrupted cache record uid=1582: UID 1582: Broken virtual size in mailbox junk: read(/home/anarcat/Maildir/.junk/cur/1454623938.M101164P22216.marcos,S=2495,W=2578:2,S): FETCH BODY[] got too little data: 2540 vs 2578
At least this first error was automatically healed by Dovecot (by renaming the file without the W= flag). The problem is that the FETCH command fails and mbsync exits noisily. So you need to constantly restart mbsync with a silly command like:
while ! mbsync -a; do sleep 1; done

"cached message size larger than expected"
nov 16 13:53:08 marcos dovecot[3520770]: imap(anarcat)<3594402><M5JHb+zQ3NLAqAB1>: Error: Mailbox Sent: UID=19288: read(/home/anarcat/Maildir/.Sent/cur/1224790447.M898726P9811V000000000000FE06I00794FB1_0.marvin,S=2588:2,S) failed: Cached message size larger than expected (2588 > 2482, box=Sent, UID=19288) (read reason=mail stream)
nov 16 13:53:08 marcos dovecot[3520770]: imap(anarcat)<3594402><M5JHb+zQ3NLAqAB1>: Error: Mailbox Sent: Deleting corrupted cache record uid=19288: UID 19288: Broken physical size in mailbox Sent: read(/home/anarcat/Maildir/.Sent/cur/1224790447.M898726P9811V000000000000FE06I00794FB1_0.marvin,S=2588:2,S) failed: Cached message size larger than expected (2588 > 2482, box=Sent, UID=19288)
nov 16 13:53:08 marcos dovecot[3520770]: imap(anarcat)<3594402><M5JHb+zQ3NLAqAB1>: Error: Mailbox Sent: UID=19288: read(/home/anarcat/Maildir/.Sent/cur/1224790447.M898726P9811V000000000000FE06I00794FB1_0.marvin,S=2588:2,S) failed: Cached message size larger than expected (2588 > 2482, box=Sent, UID=19288) (read reason=)
nov 16 13:53:08 marcos dovecot[3520770]: imap-login: Panic: epoll_ctl(del, 7) failed: Bad file descriptor
This second problem is much harder to fix, because dovecot does not recover automatically. This is Dovecot complaining that the cached size (the S= field, but also present in Dovecot's metadata files) doesn't match the file size. I wonder if at least some of those messages were corrupted in the OfflineIMAP to syncmaildir migration because part of that procedure is to run the strip_header script to remove content from the emails. That could easily have broken things since the files do not also get renamed.

Workaround So I read a lot of the Dovecot documentation on the maildir format, and wrote an extensive fix script for those two errors. The script worked and mbsync was able to sync the entire mail spool. And no, rebuilding the index files didn't work. Also tried doveadm force-resync -u anarcat which didn't do anything. In the end I also had to do this, because the wrong cache values were also stored elsewhere.
service dovecot stop ; find -name 'dovecot*' -delete; service dovecot start
This would have totally broken any existing clients, but thankfully I'm starting from scratch (except maybe webmail, but I'm hoping it will self-heal as well, assuming it only has a cache and not a full replica of the mail spool).

Incoherence between Maildir and IMAP Unfortunately, the first mbsync was incomplete as it was missing about 15,000 mails:
anarcat@angela:~(main)$ find Maildir -type f -type f -a \! -name '.*'   wc -l 
384836
anarcat@angela:~(main)$ find Maildir-mbsync/ -type f -a \! -name '.*'   wc -l 
369221
As it turns out, mbsync was not at fault here either: this was yet more mail spool corruption. It's actually 26 folders (out of 205) with inconsistent sizes, which can be found with:
for folder in * .[^.]* ; do 
  printf "%s\t%d\n" $folder $(find "$folder" -type f -a \! -name '.*'   wc -l );
done
The special \! -name '.*' bit is to ignore the mbsync metadata, which creates .uidvalidity and .mbsyncstate in every folder. That ignores about 200 files but since they are spread around all folders, which was making it impossible to review where the problem was. Here is what the diff looks like:
--- Maildir-list    2021-11-17 20:42:36.504246752 -0500
+++ Maildir-mbsync-list 2021-11-17 20:18:07.731806601 -0500
@@ -6,16 +6,15 @@
[...]
 .Archives  1
 .Archives.2010 3553
-.Archives.2011 3583
-.Archives.2012 12593
+.Archives.2011 3582
+.Archives.2012 620
 .Archives.2013 8576
 .Archives.2014 11057
-.Archives.2015 8173
+.Archives.2015 8165
 .Archives.2016 54
 .band  34
 .bitbuck   1
@@ -38,13 +37,12 @@
 .couchsurfers  2
-cur    11285
+cur    11280
 .current   130
 .cv    2
 .debbug    262
-.debian    37544
-drafts 1
-.Drafts    4
+.debian    37533
+.Drafts    2
 .drone 241
 .drupal    188
 .drupal-devel  303
[...]

Misfiled messages It's a bit all over the place, but we can already notice some huge differences between mailboxes, for example in the Archives folders. As it turns out, at least 12,000 of those missing mails were actually misfiled: instead of being in the Maildir/.Archives.2012/cur/ folder, they were directly in Maildir/.Archives.2012/. This is something that doesn't matter for SMD (and possibly for notmuch? it does matter, notmuch suddenly found 12,000 new mails) but that definitely matters to Dovecot and therefore mbsync... After moving those files around, we still have 4,000 message missing:
anarcat@angela:~(main)$ find Maildir-mbsync/  -type f -a \! -name '.*'   wc -l 
381196
anarcat@angela:~(main)$ find Maildir/  -type f -a \! -name '.*'   wc -l 
385053
The problem is that those 4,000 missing mails are harder to track. Take, for example, .Archives.2011, which has a single message missing, out of 3,582. And the files are not identical: the checksums don't match after going through the IMAP transport, so we can't use a tool like hashdeep to compare the trees and find why any single file is missing.

"register" folder One big chunk of the 4,000, however, is a special folder called register in my spool, which I am syncing separately (see Securing registration email for details on that setup). That actually covers 3,700 of those messages, so I actually have a more modest 300 messages to figure out, after (easily!) configuring mbsync to sync that folder separately:
 @@ -30,9 +33,29 @@ Slave :anarcat-local:
  # Exclude everything under the internal [Gmail] folder, except the interesting folders
  #Patterns * ![Gmail]* "[Gmail]/Sent Mail" "[Gmail]/Starred" "[Gmail]/All Mail"
  # Or include everything
 -Patterns *
 +#Patterns *
 +Patterns * !register  !.register
  # Automatically create missing mailboxes, both locally and on the server
  #Create Both
  Create slave
  # Sync the movement of messages between folders and deletions, add after making sure the sync works
  #Expunge Both
 +
 +IMAPAccount anarcat-register
 +Host imap.anarc.at
 +User register
 +PassCmd "pass imap.anarc.at-register"
 +SSLType IMAPS
 +CertificateFile /etc/ssl/certs/ca-certificates.crt
 +
 +IMAPStore anarcat-register-remote
 +Account anarcat-register
 +
 +MaildirStore anarcat-register-local
 +SubFolders Maildir++
 +Inbox ~/Maildir-mbsync/.register/
 +
 +Channel anarcat-register
 +Master :anarcat-register-remote:
 +Slave :anarcat-register-local:
 +Create slave

"tmp" folders and empty messages After syncing the "register" messages, I end up with the measly little 160 emails out of sync:
anarcat@angela:~(main)$ find Maildir-mbsync/  -type f -a \! -name '.*'   wc -l 
384900
anarcat@angela:~(main)$ find Maildir/  -type f -a \! -name '.*'   wc -l 
385059
Argh. After more digging, I have found 131 mails in the tmp/ directories of the client's mail spool. Mysterious! On the server side, it's even more files, and not the same ones. Possible that those were mails that were left there during a failed delivery of some sort, during a power failure or some sort of crash? Who knows. It could be another race condition in SMD if it runs while mail is being delivered in tmp/... The first thing to do with those is to cleanup a bunch of empty files (21 on angela):
find .[^.]*/tmp -type f -empty -delete
As it turns out, they are all duplicates, in the sense that notmuch can easily find a copy of files with the same message ID in its database. In other words, this hairy command returns nothing
find .[^.]*/tmp -type f   while read path; do
  msgid=$(grep -m 1  -i ^message-id "$path"   sed 's/Message-ID: //i;s/[<>]//g');
  if notmuch count --exclude=false  "id:$msgid"   grep -q 0; then
    echo "$path <$msgid> not in notmuch" ;
  fi;
done
... which is good. Or, to put it another way, this is safe:
find .[^.]*/tmp -type f -delete
Poof! 314 mails cleaned on the server side. Interestingly, SMD doesn't pick up on those changes at all and still sees files in tmp/ directories on the client side, so we need to operate the same twisted logic there.

notmuch to the rescue again After cleaning that on the client, we get:
anarcat@angela:~(main)$ find Maildir/  -type f -a \! -name '.*'   wc -l 
384928
anarcat@angela:~(main)$ find Maildir-mbsync/  -type f -a \! -name '.*'   wc -l 
384901
Ha! 27 mails difference. Those are the really sticky, unclear ones. I was hoping a full sync might clear that up, but after deleting the entire directory and starting from scratch, I end up with:
anarcat@angela:~(main)$ find Maildir -type f -type f -a \! -name '.*'   wc -l 
385034
anarcat@angela:~(main)$ find Maildir-mbsync -type f -type f -a \! -name '.*'   wc -l 
384993
That is: even more messages missing (now 37). Sigh. Thankfully, this is something notmuch can help with: it can index all files by Message-ID (which I learned is case-insensitive, yay) and tell us which messages don't make it through. Considering the corruption I found in the mail spool, I wouldn't be the least surprised those messages are just skipped by the IMAP server. Unfortunately, there's nothing on the Dovecot server logs that would explain the discrepancy. Here again, notmuch comes to the rescue. We can list all message IDs to figure out that discrepancy:
notmuch search --exclude=false --output=messages '*'   pv -s 18M   sort > Maildir-msgids
notmuch --config=.notmuch-config-mbsync search --exclude=false --output=messages '*'   pv -s 18M   sort > Maildir-mbsync-msgids
And then we can see how many messages notmuch thinks are missing:
$ wc -l *msgids
372723 Maildir-mbsync-msgids
372752 Maildir-msgids
That's 29 messages. Oddly, it doesn't exactly match the find output:
anarcat@angela:~(main)$ find Maildir-mbsync -type f -type f -a \! -name '.*'   wc -l 
385204
anarcat@angela:~(main)$ find Maildir -type f -type f -a \! -name '.*'   wc -l 
385241
That is 10 more messages. Ugh. But actually, I know what those are: more misfiled messages (in a .folder/draft/ directory, bizarrely, so the totals actually match. In the notmuch output, there's a lot of stuff like this:
id:notmuch-sha1-fb880d673e24f5dae71b6b4d825d4a0d5d01cde4
Those are messages without a valid Message-ID. Notmuch (presumably) constructs one based on the file's checksum. Because the files differ between the IMAP server and the local mail spool (which is unfortunate, but possibly inevitable), those do not match. There are exactly the same number of those on both sides, so I'll go ahead and assume those are all accounted for. What remains is:
anarcat@angela:~(main)$ diff -u Maildir-mbsync-msgids Maildir-msgids    grep '^\-[^-]'   grep -v sha1   wc -l 
2
anarcat@angela:~(main)$ diff -u Maildir-mbsync-msgids Maildir-msgids    grep '^\+[^+]'   grep -v sha1   wc -l 
21
anarcat@angela:~(main)$ 
ie. 21 missing from mbsync, and, surprisingly, 2 missing from the original mail spool. Further inspection also showed they were all messages with some sort of "corruption": no body and only headers. I am not sure that is a legal email format in the first place. Since they were mostly spam or administrative emails ("You have been unsubscribed from mailing list..."), it seems fairly harmless to ignore those.

Conclusion As we'll see in the next article, SMD has stellar performance. But that comes at a huge cost: it accesses the mail storage directly. This can (and has) created significant problems on the mail server. It's unclear exactly why those things happen, but Dovecot expects a particular storage format on its file, and it seems unwise to bypass that. In the future, I'll try to remember to avoid that, especially since mechanisms like SMD require special server access (SSH) which, in the long term, I am not sure I want to maintain or expect. In other words, just talking with an IMAP server opens up a lot more possibilities of hosting than setting up a custom synchronisation protocol over SSH. It's also safer and more reliable, as we have seen. Thankfully, I've been able to recover from all the errors I could find, but it could have gone differently and it would have been possible for SMD to permanently corrupt significant part of my mail archives. In the end, however, the last drop was just another weird bug which, ironically, SMD mysteriously recovered from on its own while I was writing this documentation and migrating away from it. In any case, I recommend SMD users start looking for alternatives. The project has been archived upstream, and the Debian package has been orphaned. I have seen significant mail box corruption, including entire mail spool destruction, mostly due to incorrect locking code. I have filed a release-critical bug in Debian to make sure it doesn't ship with Debian bookworm. Alternatives like mbsync provide fast and reliable transport, including over SSH. See the next article for further discussion of the alternatives.

20 June 2021

Russ Allbery: Review: The Magician's Nephew

Review: The Magician's Nephew, by C.S. Lewis
Illustrator: Pauline Baynes
Series: Chronicles of Narnia #6
Publisher: Collier Books
Copyright: 1955
Printing: 1978
ISBN: 0-02-044230-0
Format: Mass market
Pages: 186
The Magician's Nephew is the sixth book of the Chronicles of Narnia in the original publication order, but it's a prequel, set fifty years before The Lion, the Witch and the Wardrobe. It's therefore put first in the new reading order. I have always loved world-building and continuities and, as a comics book reader (Marvel primarily), developed a deep enjoyment of filling in the pieces and reconstructing histories from later stories. It's no wonder that I love reading The Magician's Nephew after The Lion, the Witch and the Wardrobe. The experience of fleshing out backstory with detail and specifics makes me happy. If that's also you, I recommend the order in which I'm reading these books. Reading this one first is defensible, though. One of the strongest arguments for doing so is that it's a much stronger, tighter, and better-told story than The Lion, the Witch and the Wardrobe, and therefore might start the series off on a better foot for you. It stands alone well; you don't need to know any of the later events to enjoy this, although you will miss the significance of a few things like the lamp post and you don't get the full introduction to Aslan. The Magician's Nephew is the story of Polly Plummer, her new neighbor Digory Kirke, and his Uncle Andrew, who fancies himself a magician. At the start of the book, Digory's mother is bed-ridden and dying and Digory is miserable, which is the impetus for a friendship with Polly. The two decide to explore the crawl space of the row houses in which they live, seeing if they can get into the empty house past Digory's. They don't calculate the distances correctly and end up in Uncle Andrew's workroom, where Digory was forbidden to go. Uncle Andrew sees this as a golden opportunity to use them for an experiment in travel to other worlds. MAJOR SPOILERS BELOW. The Magician's Nephew, like the best of the Narnia books, does not drag its feet getting started. It takes a mere 30 pages to introduce all of the characters, establish a friendship, introduce us to a villain, and get both of the kids into another world. When Lewis is at his best, he has an economy of storytelling and a grasp of pacing that I wish was more common. It's also stuffed to the brim with ideas, one of the best of which is the Wood Between the Worlds. Uncle Andrew has crafted pairs of magic rings, yellow and green, and tricks Polly into touching one of the yellow ones, causing her to vanish from our world. He then uses her plight to coerce Digory into going after her, carrying two green rings that he thinks will bring people back into our world, and not incidentally also observing that world and returning to tell Uncle Andrew what it's like. But the world is more complicated than he thinks it is, and the place where the children find themselves is an eerie and incredibly peaceful wood, full of grass and trees but apparently no other living thing, and sprinkled with pools of water. This was my first encounter with the idea of a world that connects other worlds, and it remains the most memorable one for me. I love everything about the Wood: the simplicity of it, the calm that seems in part to be a defense against intrusion, the hidden danger that one might lose one's way and confuse the ponds for each other, and even the way that it tends to make one lose track of why one is there or what one is trying to accomplish. That quiet forest filled with pools is still an image I use for infinite creativity and potential. It's quiet and nonthreatening, but not entirely inviting either; it's magnificently neutral, letting each person bring what they wish to it. One of the minor plot points of this book is that Uncle Andrew is wrong about the rings because he's wrong about the worlds. There aren't just two worlds; there are an infinite number, with the Wood as a nexus, and our reality is neither the center nor one of an important pair. The rings are directional, but relative to the Wood, not our world. The kids, who are forced to experiment and who have open minds, figure this out quickly, but Uncle Andrew never shifts his perspective. This isn't important to the story, but I've always thought it was a nice touch of world-building. Where this story is heading, of course, is the creation of Narnia and the beginning of all of the stories told in the rest of the series. But before that, the kids's first trip out of the Wood is to one of the best worlds of children's fantasy: Charn. If the Wood is my mental image of a world nexus, Charn will forever be my image of a dying world: black sky, swollen red sun, and endless abandoned and crumbling buildings as far as the eye can see, full of tired silences and eerie noises. And, of course, the hall of statues, with one of the most memorable descriptions of history and empire I've ever read (if you ignore the racialized description):
All of the faces they could see were certainly nice. Both the men and women looked kind and wise, and they seemed to come of a handsome race. But after the children had gone a few steps down the room they came to faces that looked a little different. These were very solemn faces. You felt you would have to mind your P's and Q's, if you ever met living people who looked like that. When they had gone a little farther, they found themselves among faces they didn't like: this was about the middle of the room. The faces here looked very strong and proud and happy, but they looked cruel. A little further on, they looked crueller. Further on again, they were still cruel but they no longer looked happy. They were even despairing faces: as if the people they belonged to had done dreadful things and also suffered dreadful things.
The last statue is of a fierce, proud woman that Digory finds strikingly beautiful. (Lewis notes in an aside that Polly always said she never found anything specially beautiful about her. Here, as in The Silver Chair, the girl is the sensible one and things would have gone better if the boy had listened to her, a theme that I find immensely frustrating because Susan was the sensible one in the first two books of the series but then Lewis threw that away.) There is a bell in the middle of this hall, and the pillar that holds that bell has an inscription on it that I think every kid who grew up on Narnia knows by heart.
Make your choice, adventurous Stranger;
Strike the bell and bide the danger,
Or wonder, till it drives you mad,
What would have followed if you had.
Polly has no intention of striking the bell, but Digory fights her and does it anyway, waking Jadis from where she sat as the final statue in the hall and setting off one of the greatest reimaginings of a villain in children's literature. Jadis will, of course, become the White Witch who holds Narnia in endless winter some thousand Narnian years later. But the White Witch was a mediocre villain at best, the sort of obvious and cruel villain common in short fairy tales where the author isn't interested in doing much characterization. She exists to be evil, do bad things, and be defeated. She has a few good moments in conflict with Aslan, but that's about it. Jadis in this book is another matter entirely: proud, brilliant, dangerous, and creative. The death of everything on Charn was Jadis's doing: an intentional spell, used to claim a victory of sorts from the jaws of defeat by her sister in a civil war. (I find it fascinating that Lewis puts aside his normally sexist roles here.) Despite the best attempts of the kids to lose her both in Charn and in the Wood (which is inimical to her, in another nice bit of world-building), she manages to get back to England with them. The result is a remarkably good bit of villain characterization. Jadis is totally out of her element, used to a world-spanning empire run with magic and (from what hints we get) vaguely medieval technology. Her plan to take over their local country and eventually the world should be absurd and is played somewhat for laughs. Her magic, which is her great weapon, doesn't even work in England. But Jadis learns at a speed that the reader can watch. She's observant, she pays attention to things that don't fit her expectations, she changes plans, and she moves with predatory speed. Within a few hours in London she's stolen jewels and a horse and carriage, and the local police seem entirely overmatched. There's no way that one person without magic should be a real danger to England around the turn of the 20th century, but by the time the kids manage to pull her back into the Wood, you're not entirely sure England would have been safe. A chaotic confrontation, plus the ability of the rings to work their magic through transitive human contact, ends up with the kids, Uncle Andrew, Jadis, a taxicab driver and his horse all transported through the Wood to a new world. In this case, literally a new world: Narnia at the point of its creation. Here again, Lewis translates Christian myth, in this case the Genesis creation story, into a more vivid and in many ways more beautiful story than the original. Aslan singing the world into existence is an incredible image, as is the newly-created world so bursting with life that even things that normally could not grow will do so. (Which, of course, is why there is a lamp post burning in the middle of the western forest of Narnia for the Pevensie kids to find later.) I think my favorite part is the creation of the stars, but the whole sequence is great. There's also an insightful bit of human psychology. Uncle Andrew can't believe that a lion is singing, so he convinces himself that Aslan is not singing, and thus prevents himself from making any sense of the talking animals later.
Now the trouble about trying to make yourself stupider than you really are is that you very often succeed.
As with a lot in Lewis, he probably meant this as a statement about faith, but it generalizes well beyond the religious context. What disappointed me about the creation story, though, is the animals. I didn't notice this as a kid, but this re-read has sensitized me to how Lewis consistently treats the talking animals as less than humans even though he celebrates them. That happens here too: the newly-created, newly-awakened animals are curious and excited but kind of dim. Some of this is an attempt to show that they're young and are just starting to learn, but it also seems to be an excuse for Aslan to set up a human king and queen over them instead of teaching them directly how to deal with the threat of Jadis who the children inadvertently introduced into the world. The other thing I dislike about The Magician's Nephew is that the climax is unnecessarily cruel. Once Digory realizes the properties of the newly-created world, he hopes to find a way to use that to heal his mother. Aslan points out that he is responsible for Jadis entering the world and instead sends him on a mission to obtain a fruit that, when planted, will ward Narnia against her for many years. The same fruit would heal his mother, and he has to choose Narnia over her. (It's a fairly explicit parallel to the Garden of Eden, except in this case Digory passes.) Aslan, in the end, gives Digory the fruit of the tree that grows, which is still sufficient to heal his mother, but this sequence made me angry when re-reading it. Aslan knew all along that what Digory is doing will let him heal his mother as well, but hides this from him to make it more of a test. It's cruel and mean; Aslan could have promised to heal Digory's mother and then seen if he would help Narnia without getting anything in return other than atoning for his error, but I suppose that was too transactional for Lewis's theology or something. Meh. But, despite that, the only reason why this is not the best Narnia book is because The Voyage of the Dawn Treader is the only Narnia book that also nails the ending. The Magician's Nephew, up through Charn, Jadis's rampage through London, and the initial creation of Narnia, is fully as good, perhaps better. It sags a bit at the end, partly because it tries to hard to make the Narnian animals humorous and partly because of the unnecessary emotional torture of Digory. But this still holds up as the second-best Narnia book, and one I thoroughly enjoyed re-reading. If anything, Jadis and Charn are even better than I remembered. Followed by the last book of the series, the somewhat notorious The Last Battle. Rating: 9 out of 10

29 March 2021

Jamie McClelland: The problem with Richard Stallman is not about free speech

Free speech and censorship are critically important issues. And, using them to defend Richard Stallman's return to the Free Software Foundation (FSF) board is just plain wrong. Richard Stallman resigned from the Board in 2019 after he sent an email in defense of Marvin Minsky (Minsky is accused of raping one of Jeffreys Epstein's victims). Stallman's fateful email, however, is just one piece of the reason for why he should not be on the board. The full story is about his history of abuse toward women and is extensive. On March 21st, 2021, Stallman announced he is back on the board. There are profound reasons why any movement interested in equitable and open participation would want to publicly distance themselves from Stallman. However, the long form defenses of Stallman, including a note from Nadine Strossen, the former executive director of the ACLU, quoted in this defense, persist. Many of the arguments defending Richard Stallman (including the one from Strossen) are grounded in a belief that Stallman is being punished for his unpopular political views, which deserve to be defended on the grounds of freedom of expression. That's wrong. Stallman should be kicked off the board because he has a long history of abusing his position to hit on women, which, when combined with his public opinions on under-age sex and his defense of Minsky, send a strong signal that the FSF does not care about the participation of women. Being on a board of directors is a privilege, not a right. Being removed from a board is not a punnishment. And being criticized and removed from a board because your behavior and public statements are an obstacle to building an inclusive and equitable movement is what every board should strive to do. If we are going to make this an issue about free expression, it should be about all the political expression lost to the free software movement because Stallman's unequal behavior toward women excluded an enormous number of talented individuals.

16 December 2020

Jonathan McDowell: DeskPi Pro + 8GB Pi 4

DeskPi Pro Raspberry Pi case Despite having worked on a number of ARM platforms I ve never actually had an ARM based development box at home. I have a Raspberry Pi B Classic (the original 256MB rev 0002 variant) a coworker gave me some years ago, but it s not what you d choose for a build machine and generally gets used as a self contained TFTP/console server for hooking up to devices under test. Mostly I ve been able to do kernel development with the cross compilers already built as part of Debian, and either use pre-built images or Debian directly when I need userland pieces. At a previous job I had a Marvell MACCHIATObin available to me, which works out as a nice platform - quad core A72 @ 2GHz with 16GB RAM, proper SATA and a PCIe slot. However they re still a bit pricey for a casual home machine. I really like the look of the HoneyComb LX2 - 16 A72 cores, up to 64GB RAM - but it s even more expensive. So when I saw the existence of the 8GB Raspberry Pi 4 I was interested. Firstly, the Pi 4 is a proper 64 bit device (my existing Pi B is ARMv6 which means it needs to run Raspbian instead of native Debian armhf), capable of running an upstream kernel and unmodified Debian userspace. Secondly the Pi 4 has a USB 3 controller sitting on a PCIe bus rather than just the limited SoC USB 2 controller. It s not SATA, but it s still a fairly decent method of attaching some storage that s faster/more reliable than an SD card. Finally 8GB RAM is starting to get to a decent amount - for a headless build box 4GB is probably generally enough, but I wanted some headroom. The Pi comes as a bare board, so I needed a case. Ideally I wanted something self contained that could take the Pi, provide a USB/SATA adaptor and take the drive too. I came across the pre-order for the DeskPi Pro, decided it was the sort of thing I was after, and ordered one towards the end of September. It finally arrived at the start of December, at which point I got round to ordering a Pi 4 from CPC. Total cost ~ 120 for the case + Pi.

The Bad First, let s get the bad parts out of the way. Broken USB port (right) I managed to break a USB port on the Desk Pi. It has a pair of forward facing ports, I plugged my wireless keyboard dongle into it and when trying to remove it the solid spacer bit in the socket broke off. I ve never had this happen to me before and I ve been using USB devices for 20 years, so I m putting the blame on a shoddy socket. The first drive I tried was an old Crucial M500 mSATA device. I have an adaptor that makes it look like a normal 2.5 drive so I used that. Unfortunately it resulted in a boot loop; the Pi would boot its initial firmware, try to talk to the drive and then reboot before even loading Linux. The DeskPi Pro comes with an m2 adaptor and I had a spare m2 drive, so I tried that and it all worked fine. This might just be power issues, but it was an unfortunate experience especially after the USB port had broken off. (Given I ended up using an M.2 drive another case option would have been the Argon ONE M.2, which is a bit more compact.)

The Annoying DeskPi Pro without rear bezel The case is a little snug; I was worried I was going to damage things as I slid it in. Additionally the construction process is a little involved. There s a good set of instructions, but there are a lot of pieces and screws involved. This includes a couple of FFC cables to join things up. I think this is because they ve attempted to make a compact case rather than allowing a little extra room, and it does have the advantage that once assembled it feels robust without anything loose in it. DeskPi Pro with rear bezel and USB3 dongle I hate the need for an external USB3 dongle to bridge from the Pi to the USB/SATA adaptor. All the cases I ve seen with an internal drive bay have to do this, because the USB3 isn t brought out internally by the Pi, but it just looks ugly to me. It s hidden at the back, but meh. Fan control is via a USB/serial device, which is fine, but it attaches to the USB C power port which defaults to being a USB peripheral. Raspbian based kernels support device tree overlays which allows easy reconfiguration to host mode, but for a Debian based system I ended up rolling my own dtb file. I changed
#include "bcm283x-rpi-usb-peripheral.dtsi"
to
#include "bcm283x-rpi-usb-host.dtsi"
in arch/arm/boot/dts/bcm2711-rpi-4-b.dts and then I did:
cpp -nostdinc -I include -I arch -undef -x assembler-with-cpp \
    arch/arm/boot/dts/bcm2711-rpi-4-b.dts > rpi4.preprocessed
dtc -I dts -O dtb rpi4.preprocessed -o bcm2711-rpi-4-b.dtb
and the resulting bcm2711-rpi-4-b.dtb file replaced the one in /boot/firmware. This isn t a necessary step if you don t want to use the cooling fan in the case, or the front USB ports, and it s not really anyone s fault, but it was an annoying extra step to have to figure out. The DeskPi came with a microSD card that was supposed to have RaspiOS already on it. It didn t, it was blank. In my case that was fine, because I wanted to use Debian, but it was a minor niggle.

The Good I used Gunnar s pre-built Pi Debian image and it Just Worked; I dd d it to the microSD as instructed and the Pi 4 came up with working wifi, video and USB enabling me to get it configured for my network. I did an apt upgrade and got updated to the Buster 10.7 release, as well as the latest 5.9 backport kernel, and everything came back without effort after a reboot. It s lovely to be able to run Debian on this device without having to futz around with self-compiled kernels. The DeskPi makes a lot of effort to route things externally. The SD slot is brought out to the front, making it easy to fiddle with the card contents without having to open the case to replace it. All the important ports are brought out to the back either through orientation of the Pi, or extenders in the case. That means the built in Pi USB ports, the HDMI sockets (conveniently converted to full size internally), an audio jack and a USB-C power port. The aforementioned USB3 dongle for the bridge to the drive is the only external thing that s annoying. Thermally things seem good too. I haven t done a full torture test yet, but with the fan off the system is sitting at about 40 C while fairly idle. Some loops in bash that push load up to above 2 get the temperature up to 46 C or so, and turning the fan on brings it down to 40 C again. It s audible, but quieter than my laptop and not annoying. I liked the way the case came with everything I needed other than the Pi 4 and a suitable disk drive. There was an included PSU (a proper USB-C PD device, UK plug), the heatsink/fan is there, the USB/SATA converter is there and even an SD card is provided (though that s just because I had a pre-order). Speaking of the SD, I only needed it for initial setup. Recent Pi 4 bootloaders are capable of booting directly from USB mass storage devices. So I upgraded using the RPi EEPROM Recovery image (which just needs extracted to the SD FAT partition, no need for anything complicated - boot with it and the screen goes all green and you know it s ok), then created a FAT partition at the start of the drive for the kernel / bootloader config and a regular EXT4 partition for root. Copies everything over, updated paths, took out the SD and it all just works happily.

Summary My main complaint is the broken USB port, which feels like the result of a cheap connector. For a front facing port expected to see more use than the rear ports I think there s a reasonable expectation of robustness. However I m an early adopter and maybe future runs will be better. Other than that I m pretty happy. The case is exactly the sort of thing I wanted; I was looking for something that would turn the Pi into a box that can sit on my desk on the network and that I don t have to worry about knocking wires out of or lots of cables hooking bits up. Everything being included made it very convenient to get up and running. I still haven t poked the Pi that hard, but first impressions are looking good for it being a trouble free ARM64 dev box in the corner, until I can justify a HoneyComb.

19 October 2020

Louis-Philippe V ronneau: Musings on long-term software support and economic incentives

Although I still read a lot, during my college sophomore years my reading habits shifted from novels to more academic works. Indeed, reading dry textbooks and economic papers for classes often kept me from reading anything else substantial. Nowadays, I tend to binge read novels: I won't touch a book for months on end, and suddenly, I'll read 10 novels back to back1. At the start of a novel binge, I always follow the same ritual: I take out my e-reader from its storage box, marvel at the fact the battery is still pretty full, turn on the WiFi and check if there are OS updates. And I have to admit, Kobo Inc. (now Rakuten Kobo) has done a stellar job of keeping my e-reader up to date. I've owned this model (a Kobo Aura 1st generation) for 7 years now and I'm still running the latest version of Kobo's Linux-based OS. Having recently had trouble updating my Nexus 5 (also manufactured 7 years ago) to Android 102, I asked myself:
Why is my e-reader still getting regular OS updates, while Google stopped issuing security patches for my smartphone four years ago?
To try to answer this, let us turn to economic incentives theory. Although not the be-all and end-all some think it is3, incentives theory is not a bad tool to analyse this particular problem. Executives at Google most likely followed a very business-centric logic when they decided to drop support for the Nexus 5. Likewise, Rakuten Kobo's decision to continue updating older devices certainly had very little to do with ethics or loyalty to their user base. So, what are the incentives that keep Kobo updating devices and why are they different than smartphone manufacturers'? A portrait of the current long-term software support offerings for smartphones and e-readers Before delving deeper in economic theory, let's talk data. I'll be focusing on 2 brands of e-readers, Amazon's Kindle and Rakuten's Kobo. Although the e-reader market is highly segmented and differs a lot based on geography, Amazon was in 2015 the clear worldwide leader with 53% of the worldwide e-reader sales, followed by Rakuten Kobo at 13%4. On the smartphone side, I'll be differentiating between Apple's iPhones and Android devices, taking Google as the barometer for that ecosystem. As mentioned below, Google is sadly the leader in long-term Android software support. Rakuten Kobo According to their website and to this Wikipedia table, the only e-readers Kobo has deprecated are the original Kobo eReader and the Kobo WiFi N289, both released in 2010. This makes their oldest still supported device the Kobo Touch, released in 2011. In my book, that's a pretty good track record. Long-term software support does not seem to be advertised or to be a clear selling point in their marketing. Amazon According to their website, Amazon has dropped support for all 8 devices produced before the Kindle Paperwhite 2nd generation, first sold in 2013. To put things in perspective, the first Kindle came out in 2007, 3 years before Kobo started selling devices. Like Rakuten Kobo, Amazon does not make promises of long-term software support as part of their marketing. Apple Apple has a very clear software support policy for all their devices:
Owners of iPhone, iPad, iPod or Mac products may obtain a service and parts from Apple or Apple service providers for five years after the product is no longer sold or longer, where required by law.
This means in the worst-case scenario of buying an iPhone model just as it is discontinued, one would get a minimum of 5 years of software support. Android Google's policy for their Android devices is to provide software support for 3 years after the launch date. If you buy a Pixel device just before the new one launches, you could theoretically only get 2 years of support. In 2018, Google decided OEMs would have to provide security updates for at least 2 years after launch, threatening not to license Google Apps and the Play Store if they didn't comply. A question of cost structure From the previous section, we can conclude that in general, e-readers seem to be supported longer than smartphones, and that Apple does a better job than Android OEMs, providing support for about twice as long. Even Fairphone, who's entire business is to build phones designed to last and to be repaired was not able to keep the Fairphone 1 (2013) updated for more than a couple years and seems to be struggling to keep the Fairphone 2 (2015) running an up to date version of Android. Anyone who has ever worked in IT will tell you: maintaining software over time is hard work and hard work by specialised workers is expensive. Most commercial electronic devices are sold and developed by for-profit enterprises and software support all comes down to a question of cost structure. If companies like Google or Fairphone are to be expected to provide long-term support for the devices they manufacture, they have to be able to fund their work somehow. In a perfect world, people would be paying for the cost of said long-term support, as it would likely be cheaper then buying new devices every few years and would certainly be better for the planet. Problem is, manufacturers aren't making them pay for it. Economists call this type of problem externalities: things that should be part of the cost of a good, but aren't for one a reason or another. A classic example of an externality is pollution. Clearly pollution is bad and leads to horrendous consequences, like climate change. Sane people agree we should drastically cut our greenhouse gas emissions, and yet, we aren't. Neo-classical economic theory argues the way to fix externalities like pollution is to internalise these costs, in other words, to make people pay for the "real price" of the goods they buy. In the case of climate change and pollution, neo-classical economic theory is plain wrong (spoiler alert: it often is), but this is where band-aids like the carbon tax comes from. Still, coming back to long-term software support, let's see what would happen if we were to try to internalise software maintenance costs. We can do this multiple ways. 1 - Include the price of software maintenance in the cost of the device This is the choice Fairphone makes. This might somewhat work out for them since they are a very small company, but it cannot scale for the following reasons:
  1. This strategy relies on you giving your money to an enterprise now, and trusting them to "Do the right thing" years later. As the years go by, they will eventually look at their books, see how much ongoing maintenance is costing them, drop support for the device, apologise and move on. That is to say, enterprises have a clear economic incentive to promise long-term support and not deliver. One could argue a company's reputation would suffer from this kind of behaviour. Maybe sometime it does, but most often people forget. Political promises are a great example of this.
  2. Enterprises go bankrupt all the time. Even if company X promises 15 years of software support for their devices, if they cease to exist, your device will stop getting updates. The internet is full of stories of IoT devices getting bricked when the parent company goes bankrupt and their servers disappear. This is related to point number 1: to some degree, you have a disincentive to pay for long-term support in advance, as the future is uncertain and there are chances you won't get the support you paid for.
  3. Selling your devices at a higher price to cover maintenance costs does not necessarily mean you will make more money overall raising more money to fund maintenance costs being the goal here. To a certain point, smartphone models are substitute goods and prices higher than market prices will tend to drive consumers to buy cheaper ones. There is thus a disincentive to include the price of software maintenance in the cost of the device.
  4. People tend to be bad at rationalising the total cost of ownership over a long period of time. Economists call this phenomenon hyperbolic discounting. In our case, it means people are far more likely to buy a 500$ phone each 3 years than a 1000$ phone each 10 years. Again, this means OEMs have a clear disincentive to include the price of long-term software maintenance in their devices.
Clearly, life is more complex than how I portrayed it: enterprises are not perfect rational agents, altruism exists, not all enterprises aim solely for profit maximisation, etc. Still, in a capitalist economy, enterprises wanting to charge for software maintenance upfront have to overcome these hurdles one way or another if they want to avoid failing. 2 - The subscription model Another way companies can try to internalise support costs is to rely on a subscription-based revenue model. This has multiple advantages over the previous option, mainly:
  1. It does not affect the initial purchase price of the device, making it easier to sell them at a competitive price.
  2. It provides a stable source of income, something that is very valuable to enterprises, as it reduces overall risks. This in return creates an incentive to continue providing software support as long as people are paying.
If this model is so interesting from an economic incentives point of view, why isn't any smartphone manufacturer offering that kind of program? The answer is, they are, but not explicitly5. Apple and Google can fund part of their smartphone software support via the 30% cut they take out of their respective app stores. A report from Sensor Tower shows that in 2019, Apple made an estimated US$ 16 billion from the App Store, while Google raked in US$ 9 billion from the Google Play Store. Although the Fortune 500 ranking tells us this respectively is "only" 5.6% and 6.5% of their gross annual revenue for 2019, the profit margins in this category are certainly higher than any of their other products. This means Google and Apple have an important incentive to keep your device updated for some time: if your device works well and is updated, you are more likely to keep buying apps from their store. When software support for a device stops, there is a risk paying customers will buy a competitor device and leave their ecosystem. This also explains why OEMs who don't own app stores tend not to provide software support for very long periods of time. Most of them only make money when you buy a new phone. Providing long-term software support thus becomes a disincentive, as it directly reduces their sale revenues. Same goes for Kindles and Kobos: the longer your device works, the more money they make with their electronic book stores. In my opinion, it's likely Amazon and Rakuten Kobo produce quarterly cost-benefit reports to decide when to drop support for older devices, based on ongoing support costs and the recurring revenues these devices bring in. Rakuten Kobo is also in a more precarious situation than Amazon is: considering Amazon's very important market share, if your device stops getting new updates, there is a greater chance people will replace their old Kobo with a Kindle. Again, they have an important economic incentive to keep devices running as long as they are profitable. Can Free Software fix this? Yes and no. Free Software certainly isn't a magic wand one can wave to make everything better, but does provide major advantages in terms of security, user freedom and sometimes costs. The last piece of the puzzle explaining why Rakuten Kobo's software support is better than Google's is technological choices. Smartphones are incredibly complex devices and have become the main computing platform of many. Similar to the web, there is a race for features and complexity that tends to create bloat and make older devices slow and painful to use. On the other hand, e-readers are simpler devices built for a single task: display electronic books. Control over the platform is also a key aspect of the cost structure of providing software updates. Whereas Apple controls both the software and hardware side of iPhones, Android is a sad mess of drivers and SoCs, all providing different levels of support over time6. If you take a look at the platforms the Kindle and Kobo are built on, you'll quickly see they both use Freescale I.MX SoCs. These processors are well known for their excellent upstream support in the Linux kernel and their relative longevity, chips being produced for either 10 or 15 years. This in turn makes updates much easier and less expensive to provide. So clearly, open architectures, free drivers and open hardware helps tremendously, but aren't enough on their own. One of the lessons we must learn from the (amazing) LineageOS project is how lack of funding hurts everyone. If there is no one to do the volunteer work required to maintain a version of LOS for your device, it won't be supported. Worse, when purchasing a new device, users cannot know in advance how many years of LOS support they will get. This makes buying new devices a frustrating hit-and-miss experience. If you are lucky, you will get many years of support. Otherwise, you risk your device becoming an expensive insecure paperweight. So how do we fix this? Anyone with a brain understands throwing away perfectly good devices each 2 years is not sustainable. Government regulations enforcing a minimum support life would be a step in the right direction, but at the end of the day, Capitalism is to blame. Like the aforementioned carbon tax, band-aid solutions can make things somewhat better, but won't fix our current economic system's underlying problems. For now though, I'll leave fixing the problem of Capitalism to someone else.

  1. My most recent novel binge has been focused on re-reading the Dune franchise. I first read the 6 novels written by Frank Herbert when I was 13 years old and only had vague and pleasant memories of his work. Great stuff.
  2. I'm back on LineageOS! Nice folks released an unofficial LOS 17.1 port for the Nexus 5 last January and have kept it updated since then. If you are to use it, I would also recommend updating TWRP to this version specifically patched for the Nexus 5.
  3. Very few serious economists actually believe neo-classical rational agent theory is a satisfactory explanation of human behavior. In my opinion, it's merely a (mostly flawed) lens to try to interpret certain behaviors, a tool amongst others that needs to be used carefully, preferably as part of a pluralism of approaches.
  4. Good data on the e-reader market is hard to come by and is mainly produced by specialised market research companies selling their findings at very high prices. Those particular statistics come from a MarketWatch analysis.
  5. If they were to tell people: You need to pay us 5$/month if you want to receive software updates, I'm sure most people would not pay. Would you?
  6. Coming back to Fairphones, if they had so much problems providing an Android 9 build for the Fairphone 2, it's because Qualcomm never provided Android 7+ support for the Snapdragon 801 SoC it uses.

24 August 2020

Ulrike Uhlig: Code reviews: from nitpicking to cooperation

After we gave our talk at DebConf 20, Doing things together, there were 5 minutes left for the live Q&A. Pollo asked a question that I think is interesting and deserves a longer answer: How can we still have a good code review process without making it a "you need to be perfect" scenario? I often find picky code reviews help me write better code. I find it useful to first disentangle what code reviews are good for, how we do them, why we do them that way, and how we can potentially improve processes. What are code reviews good for? Code review and peer review are great methods for cooperation aiming at: Looking at this list, the last point seems to be more like a nice side effect of all the other points. :) How do code reviews happen in our communities? It seems to be a common assumption that code reviews are and have to be picky and perfectionist. To me, this does not actually seem to be a necessity to accomplish the above mentioned goals. We might want to work with precision a quality which is different from perfection. Perfection can hardly be a goal: perfection does not exist. Perfectionist dynamics can lead to failing to call something "good enough" or "done". Sometimes, a disproportionate amount of time is invested in writing (several) code reviews for minor issues. In some cases, strong perfectionist dynamics of a reviewer can create a feeling of never being good enough along with a loss of self esteem for otherwise skilled code authors. When do we cross the line? When going from cooperation, precision, and learning to write better code, to nitpicking, we are crossing a line: nitpicking means to pedantically search for others' faults. For example, I once got one of my Git commits at work criticized merely for its commit message that was said to be "ugly" because I "use[d] the same word twice" in it. When we are nitpicking, we might not give feedback in an appreciative, cooperative way, we become fault finders instead. From there it's a short way to operating on the level of blame. Are you nitpicking to help or are you nitpicking to prove something? Motivations matter. How can we improve code reviewing? When we did something wrong, we can do better next time. When we are told that we are wrong, the underlying assumption is that we cannot change (See Bren Brown, The difference between blame and shame). We can learn to go beyond blame. Negative feedback rarely leads to improvement if the environment in which it happens lacks general appreciation and confirmation. We can learn to give helpful feedback. It might be harder to create an appreciative environment in which negative feedback is a possibility for growth. One can think of it like of a relationship: in a healthy relationship we can tell each other when something does not work and work it out because we regularly experience that we respect, value, and support each other. To be able to work precisely, we need guidelines, tools, and time. It's not possible to work with precision if we are in a hurry, burnt out, or working under a permanent state of exception. The same is true for receiving picky feedback. On DebConf's IRC channel, after our talk, marvil07 said: On picky code reviews, something that I find useful is automation on code reviews; i.e. when a bot is stating a list of indentation/style errors it feels less personal, and also saves time to humans to provide more insightful changes. Indeed, we can set up routines that do automatic fault checking (linting). We can set up coding guidelines. We can define what we call "done" or "good enough". We can negotiate with each other how we would like code to be reviewed. For example, one could agree that a particularly perfectionist reviewer should point out only functional faults. They can spare their time and refrain from writing lengthy reviews about minor esthetic issues that have never made it into a guideline. If necessary, author and reviewer can talk about what can be improved on the long term during a retrospective. Or, on the contrary, one could explicitly ask for a particularly detailed review including all sorts of esthetic issues to learn the best practices of a team applied to one's own code. In summary: let's not lose sight of what code reviews are good for, let's have a clear definition of "done", let's not confuse precision with perfection, let's create appreciative work environments, and negotiate with each other how reviews are made. I'm sure you will come up with more ideas. Please do not hesitate to share them!

1 July 2020

Paul Wise: FLOSS Activities June 2020

Focus This month I didn't have any particular focus. I just worked on issues in my info bubble.

Changes

Issues

Review

Administration
  • Debian BTS: usertags QA
  • Debian IRC channels: fixed a channel mode lock
  • Debian wiki: unblock IP addresses, approve accounts, ping folks with bouncing email

Communication
  • Respond to queries from Debian users and developers on the mailing lists and IRC

Sponsors The ifenslave and apt-listchanges work was sponsored by my employer. All other work was done on a volunteer basis.

6 June 2020

Petter Reinholdtsen: Secure Socket API - a simple and powerful approach for TLS support in software

As a member of the Norwegian Unix User Group, I have the pleasure of receiving the USENIX magazine ;login: several times a year. I rarely have time to read all the articles, but try to at least skim through them all as there is a lot of nice knowledge passed on there. I even carry the latest issue with me most of the time to try to get through all the articles when I have a few spare minutes. The other day I came across a nice article titled "The Secure Socket API: TLS as an Operating System Service" with a marvellous idea I hope can make it all the way into the POSIX standard. The idea is as simple as it is powerful. By introducing a new socket() option IPPROTO_TLS to use TLS, and a system wide service to handle setting up TLS connections, one both make it trivial to add TLS support to any program currently using the POSIX socket API, and gain system wide control over certificates, TLS versions and encryption systems used. Instead of doing this:
int socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
the program code would be doing this:
int socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TLS);
According to the ;login: article, converting a C program to use TLS would normally modify only 5-10 lines in the code, which is amazing when compared to using for example the OpenSSL API. The project has set up the https://securesocketapi.org/ web site to spread the idea, and the code for a kernel module and the associated system daemon is available from two github repositories: ssa and ssa-daemon. Unfortunately there is no explicit license information with the code, so its copyright status is unclear. A request to solve this about it has been unsolved since 2018-08-17. I love the idea of extending socket() to gain TLS support, and understand why it is an advantage to implement this as a kernel module and system wide service daemon, but can not help to think that it would be a lot easier to get projects to move to this way of setting up TLS if it was done with a user space approach where programs wanting to use this API approach could just link with a wrapper library. I recommend you check out this simple and powerful approach to more secure network connections. :) As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

26 May 2020

Russ Allbery: Review: The Ten Thousand Doors of January

Review: The Ten Thousand Doors of January, by Alix E. Harrow
Publisher: Redhook
Copyright: September 2019
ISBN: 0-316-42198-7
Format: Kindle
Pages: 373
In 1901, at the age of seven, January found a Door. It was barely more than a frame in a ruined house in a field in Kentucky, but she wrote a story about opening it, and then did.
Once there was a brave and temeraryous (sp?) girl who found a Door. It was a magic Door that's why it has a capital D. She opened the Door.
The Door led to a bluff over the sea and above a city, a place very far from Kentucky, and she almost stayed, but she came back through the Door when her guardian, Mr. Locke, called. The adventure cost her a diary, several lectures, days of being locked in her room, and the remnants of her strained relationship with her father. When she went back, the frame of the Door was burned to the ground. That was the end of Doors for January for some time, and the continuation of a difficult childhood. She was cared for by her father's employer as a sort of exotic pet, dutifully attempting to obey, grateful for Mr. Locke's protection, and convinced that he was occasionally sneaking her presents through a box in the Pharaoh Room out of some hidden kindness. Her father appeared rarely, said little, and refused to take her with him. Three things helped: the grocery boy who smuggled her stories, an intimidating black woman sent by her father to replace her nurse, and her dog.
Once upon a time there was a good girl who met a bad dog, and they became the very best of friends. She and her dog were inseparable from that day forward.
I will give you a minor spoiler that I would have preferred to have had, since it would have saved me some unwarranted worry and some mental yelling at the author: The above story strains but holds. January's adventure truly starts the day before her seventeenth birthday, when she finds a book titled The Ten Thousand Doors in the box in the Pharaoh Room. As you may have guessed from the title, The Ten Thousand Doors of January is a portal fantasy, but it's the sort of portal fantasy that is more concerned with the portal itself than the world on the other side of it. (Hello to all of you out there who, like me, have vivid memories of the Wood between the Worlds.) It's a book about traveling and restlessness and the possibility of escape, about the ability to return home again, and about the sort of people who want to close those doors because the possibility of change created by people moving around freely threatens the world they have carefully constructed. Structurally, the central part of the book is told by interleaving chapters of January's tale with chapters from The Ten Thousand Doors. That book within a book starts with the framing of a scholarly treatment but quickly becomes a biography of a woman: Adelaide Lee Larson, a half-wild farm girl who met her true love at the threshold of a Door and then spent much of her life looking for him. I am not a very observant reader for plot details, particularly for books that I'm enjoying. I read books primarily for the emotional beats and the story structure, and often miss rather obvious story clues. (I'm hopeless at guessing the outcomes of mysteries.) Therefore, when I say that there are many things January is unaware of that are obvious to the reader, that's saying a lot. Even more clues were apparent when I skimmed the first chapter again, and a more observant reader would probably have seen them on the first read. Right down to Mr. Locke's name, Harrow is not very subtle about the moral shape of this world. That can make the early chapters of the book frustrating. January is being emotionally (and later physically) abused by the people who have power in her life, but she's very deeply trapped by false loyalty and lack of external context. Winning free of that is much of the story of the book, and at times it has the unpleasantness of watching someone make excuses for her abuser. At other times it has the unpleasantness of watching someone be abused. But this is the place where I thought the nested story structure worked marvelously. January escapes into the story of The Ten Thousand Doors at the worst moments of her life, and the reader escapes with her. Harrow uses the desire to switch scenes back to the more adventurous and positive story to construct and reinforce the emotional structure of the book. For me, it worked extremely well. It helps that the ending is glorious. The payoff is worth all the discomfort and tension-building in the first half of the book. Both The Ten Thousand Doors and the surrounding narrative reach deeply satisfying conclusions, ones that are entangled but separate in just the ways that they need to be. January's abilities, actions, and decisions at the end of the book were just the outcome that I needed but didn't entirely guess in advance. I could barely put down the last quarter of this story and loved every moment of the conclusion. This is the sort of book that can be hard to describe in a review because its merits don't rest on an original twist or easily-summarized idea. The elements here are all elements found in other books: portal fantasy, the importance of story-telling, coming of age, found family, irrepressible and indomitable characters, and the battle of the primal freedom of travel and discovery and belief against the structural forces that keep rulers in place. The merits of this book are in the small details: the way that January's stories are sparse and rare and sometimes breathtaking, the handling of tattoos, the construction of other worlds with a few deft strokes, and the way Harrow embraces the emotional divergence between January's life and Adelaide's to help the reader synchronize the emotional structure of their reading experience with January's.
She writes a door of blood and silver. The door opens just for her.
The Ten Thousand Doors of January is up against a very strong slate for both the Nebula and the Hugo this year, and I suspect it may be edged out by other books, although I wouldn't be unhappy if it won. (It probably has a better shot at the Nebula than the Hugo.) But I will be stunned if Harrow doesn't walk away with the Mythopoeic Award. This seems like exactly the type of book that award was created for. This is an excellent book, one of the best I've read so far this year. Highly recommended. Rating: 9 out of 10

1 March 2020

Enrico Zini: Online aggression links

Sealioning - Wikipedia
privilege archive.org
Sealioning (also spelled sea-lioning and sea lioning) is a type of trolling or harassment which consists of pursuing people with persistent requests for evidence or repeated questions, while maintaining a pretense of civility and sincerity.[1][2][3][4] It may take the form of "incessant, bad-faith invitations to engage in debate".[5]
Tone policing (also tone trolling, tone argument, and tone fallacy) is an ad hominem (personal attack) and antidebate tactic based on criticizing a person for expressing emotion. Tone policing detracts from the validity of a statement by attacking the tone in which it was presented rather than the message itself.
"A brawler who tattoos a message onto his knuckles does not throw every punch with the weight of First Amendment protection behind him," the brief stated. "Conduct like this does not constitute speech, nor should it. A deliberate attempt to cause physical injury to someone does not come close to the expression which the First Amendment is designed to protect."
It s no secret that times are changing. It used to be that men were men, jokes were jokes, and all facts came from one white guy in a suit who you trusted because he looked like your dad. Now I know I could get in a lot of trouble for just saying this, but I don t care because someone has to tell the truth: These days, you can t say anything racist at all without being called a racist.
Russia's neighbor has developed a plan for countering misinformation. Can it be exported to the rest of the world?
So, I wrote my BIFF Response but Marvin wrote me another angry email. Actually, he wrote 6 more this week, so what s up with that? Why didn t he stop after my first email?
The BIFF Response Method will teach you how to respond to angry emails, texts, or social media posts while maintaining your dignity and personal power.

6 October 2017

Rapha&#235;l Hertzog: My Free Software Activities in September 2017

My monthly report covers a large part of what I have been doing in the free software world. I write it for my donors (thanks to them!) but also for the wider Debian community because it can give ideas to newcomers and it s one of the best ways to find volunteers to work with me on projects that matter to me. Debian LTS This month I was allocated 12h but I only spent 10.5h. During this time, I continued my work on exiv2. I finished reproducing all the issues and then went on doing code reviews to confirm that vulnerabilities were not present when the issue was not reproducible. I found two CVE where the vulnerability was present in the wheezy version and I posted patches in the upstream bug tracker: #57 and #55. Then another batch of 10 CVE appeared and I started the process over I m currently trying to reproduce the issues. While doing all this work on exiv2, I also uncovered a failure to build on the package in experimental (reported here). Misc Debian/Kali work Debian Live. I merged 3 live-build patches prepared by Matthijs Kooijman and added an armel fix to cope with the the rename of the orion5x image into the marvell one. I also uploaded a new live-config to fix a bug with the keyboard configuration. Finally, I also released a new live-installer udeb to cope with a recent live-build change that broke the locale selection during the installation process. Debian Installer. I prepared a few patches on pkgsel to merge a few features that had been added to Ubuntu, most notably the possibility to enable unattended-upgrades by default. More bug reports. I investigated much further my problem with non-booting qemu images when they are built by vmdebootstrap in a chroot managed by schroot (cf #872999) and while we have much more data, it s not yet clear why it doesn t work. But we have a working work-around While investigating issues seen in Kali, I opened a bunch of reports on the Debian side: Packaging. I sponsored two uploads (dirb and python-elasticsearch). Debian Handbook. My work on updating the book mostly stalled. The only thing I did was to review the patch about wireless configuration in #863496. I must really get back to work on the book! Thanks See you next month for a new summary of my activities.

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28 September 2017

Russ Allbery: Review: The Seventh Bride

Review: The Seventh Bride, by T. Kingfisher
Publisher: 47North
Copyright: 2015
ISBN: 1-5039-4975-3
Format: Kindle
Pages: 225
There are two editions of this book, although only one currently for sale. This review is of the second edition, released in November of 2015. T. Kingfisher is a pen name for Ursula Vernon when she's writing for adults. Rhea is a miller's daughter. She's fifteen, obedient, wary of swans, respectful to her parents, and engaged to Lord Crevan. The last was a recent and entirely unexpected development. It's not that she didn't expect to get married eventually, since of course that's what one does. And it's not that Lord Crevan was a stranger, since that's often how it went with marriage for people like her. But she wasn't expecting to get married now, and it was not at all clear why Lord Crevan would want to marry her in particular. Also, something felt not right about the entire thing. And it didn't start feeling any better when she finally met Lord Crevan for the first time, some days after the proposal to her parents. The decidedly non-romantic hand kissing didn't help, nor did the smug smile. But it's not like she had any choice. The miller's daughter doesn't say no to a lord and a friend of the viscount. The miller's family certainly doesn't say no when they're having trouble paying the bills, the viscount owns the mill, and they could be turned out of their livelihood at a whim. They still can't say no when Lord Crevan orders Rhea to come to his house in the middle of the night down a road that quite certainly doesn't exist during the day, even though that's very much not the sort of thing that is normally done. Particularly before the marriage. Friends of the viscount who are also sorcerers can get away with quite a lot. But Lord Crevan will discover that there's still a limit to how far he can order Rhea around, and practical-minded miller's daughters can make a lot of unexpected friends even in dire circumstances. The Seventh Bride is another entry in T. Kingfisher's series of retold fairy tales, although the fairy tale in question is less clear than with The Raven and the Reindeer. Kirkus says it's a retelling of Bluebeard, but I still don't quite see that in the story. I think one could argue equally easily that it's an original story. Nonetheless, it is a fairy tale: it has that fairy tale mix of magical danger and practical morality, and it's about courage and friendships and their consequences. It also has a hedgehog. This is an T. Kingfisher story, so it's packed full of bits of marvelous phrasing that I want to read over and over again. It has wonderful characters, the hedgehog among them, and it has, at its heart, a sort of foundational decency and stubborn goodness that's deeply satisfying for the reader. The Seventh Bride is a lot closer to horror than the other T. Kingfisher books I've read, but it never fell into my dislike of the horror genre, despite a few gruesome bits. I think that's because neither Rhea nor the narrator treat the horrific aspects as representative of the true shape of the world. Rhea instead confronts them with a stubborn determination and an attempt to make the best of each moment, and with a practical self-awareness that I loved reading about.
The problem with crying in the woods, by the side of a white road that leads somewhere terrible, is that the reason for crying isn't inside your head. You have a perfectly legitimate and pressing reason for crying, and it will still be there in five minutes, except that your throat will be raw and your eyes will itch and absolutely nothing else will have changed.
Lord Crevan, when Rhea finally reaches him, toys with her by giving her progressively more horrible puzzle tasks, threatening her with the promised marriage if she fails at any of them. The way this part of the book finally resolves is one of the best moments I've read in any book. Kingfisher captures an aspect of moral decisions, and a way in which evil doesn't work the way that evil people expect it to work, that I can't remember seeing an author capture this well. There are a lot of things here for Rhea to untangle: the nature of Crevan's power, her unexpected allies in his manor, why he proposed marriage to her, and of course how to escape his power. The plot works, but I don't think it was the best part of the book, and it tends to happen to Rhea rather than being driven by her. But I have rarely read a book quite this confident of its moral center, or quite as justified in that confidence. I am definitely reading everything Vernon has published under the T. Kingfisher name, and quite possibly most of her children's books as well. Recommended, particularly if you liked the excerpt above. There's an entire book full of paragraphs like that waiting for you. Rating: 8 out of 10

19 April 2017

Antoine Beaupr : The rise of Linux-based networking hardware

Linux usage in networking hardware has been on the rise for some time. During the latest Netdev conference held in Montreal this April, people talked seriously about Linux running on high end, "top of rack" (TOR) networking equipment. Those devices have long been the realm of proprietary hardware and software companies like Cisco or Juniper, but Linux seems to be making some significant headway into the domain. According to Shrijeet Mukherjee, VP of Engineering at Cumulus Networks: "we are seeing a 28% adoption rate in the Fortune 50" companies. As someone who has worked in system administration and networking for over a decade, I was surprised by this: switches have always been black boxes of proprietary hardware that we barely get a shell into. But as more and more TOR hardware gets Linux support, some of that work trickles down outside of that niche. Are we really seeing the rise of Linux in high-end networking hardware?

Linux as the standard interface During his keynote at Netdev, Jesse Brandeburg explained that traffic is exploding on the Internet: "From 2006 to 2016 the compound annual growth rate was 78% of network traffic. So the network traffic is growing like crazy. In 2010 to 2023, it's going to grow by a thousand times." He also mentioned Intel was working on devices that could do up to 400 Gbps. In his talk, he argued that Linux has a critical place in the modern world by repeating the mantra that "everything is on the network, and the network runs Linux", but does it really? Through Android, Linux has become the most popular end-user device operating system and is also dominant on the server but what about the actual fabric of the network: the routers and switches that interconnect all those machines? Mukherjee, in his own keynote, argued that even though Linux has achieved dominance in the server and virtualization markets, there is a "discontinuity [...] at the boundary where the host and the network meet" and argued "that the host without the network will not survive". In other words, proprietary hardware and software in the network threaten free software in the server. Even though some manufacturers are already providing a "Linux interface" in their hardware, it is often only some sort of compatibility shell which might be compared with the Ubuntu compatibility layer in Windows: it's not a real Linux. Mukherjee pushed this idea further by saying that those companies are limiting themselves by not using the full Linux stack. He presented Linux as the "top vehicle for innovation" that provides a featureful network stack, citing VXLAN, eBPF, and Quagga as prime features used on switches. Mukherjee also praised the diversity of the user-space Linux ecosystem as something that commercial alternatives can't rival; he compared the faster Linux development to the commercial sector where similar top features stay in the beta stage for up to 3 years. Because of its dominance in the server market, consumers are expecting a Linux-like interface on their networking gear now, which means Linux could be the standard interface all providers strive toward. As a Debian developer, I can't help but smile at the thought; if there's one thing we have not been able to do among Linux distributions, it's pretty much standardize user space in a consistent interface. POSIX is old and incomplete, the FHS is showing its age, and most distributions have abandoned LSB. Yet, the idea is certainly enticing: there is a base set of tools and applications, especially for the Linux kernel, that are standardized: iproute2, ethtool, and iptables are generally consistent across distributions, even though each distribution has its own way of using them. Yet Linux is not dominant, why? Mukherjee identified the problem as "packaging issues" and listed a set of features he would like Linux to improve:
  • Standardization of the ethtool interface. The idea is to make ethtool a de-facto standard to manage switches and ports. Mukherjee gave the example that data centers spend more money on cables than any other hardware and explained that making it easier to identify cables is therefore a key functionality. Getting consistent interface naming was also a key problem identified by numerous participants at the conference. While systemd tried to fix this with the predictable network interface names specification, the interface names are not necessarily predictable across virtual machines or on special hardware; in fact, this was the topic of the first talk of the conference. ethtool also needs to support interfaces that run faster than 1 Gbps, something that still has limited support in Linux at the moment.
  • Scaling of the Linux bridge. Through the rise of "software defined networking", we are likely to see multi-switch virtual environments that need to scale to hundreds of interfaces and devices easily. This is something the Linux bridge was never designed to do and it's showing scalability issues. During the conference, there was hope that the new XDP and eBPF developments could help, but also concerns this would create yet another bridge layer inside the kernel.
Cumulus's goal seems to be to establish Linux as the industry standard for this new era of networking and it is not alone. Through its Open Compute project, Facebook is sharing open designs of data center products and, while we have yet to see commercial off-the-shelf (COTS) 24 and 48-port gigabit switches trickle down to the consumer market, the company is definitely deploying new hardware based on those specifications in its own data centers, and those devices are often based on Linux.

The Linux switch implementation So how exactly do switches work in Linux? The Linux kernel manipulates switches with three different operation structures: switchdev_ops, which we previously covered, ethtool_ops, and netdev_ops. Certain switches, however, also need distributed switch architecture (DSA) features to be properly handled. DSA is a more obscure part of the network stack that allows Linux to represent hardware switches or chains of switches using regular Linux tools like bridge, ifconfig, and so on. While switchdev is a new layer, DSA has been in the kernel since 2.6.28 in 2008. Originally developed to support Marvell switches, DSA is now a generic layer deployed in WiFi access points, set-top boxes, on-board flight entertainment systems, trains, and other industrial equipment. Switches that have an Ethernet controller need DSA, whereas the kernel can support switches without Ethernet controllers directly with switchdev drivers. The first years of DSA's development consisted only of basic maintenance but, in the last three years, DSA has seen a resurgence of contributions, as part of Linux networking push to support hardware offloading and network switches. Between 2014 and 2015, DSA added support for Broadcom hardware, wake on LAN, and hardware port bridging, among other features. DSA's development was parallel to swconfig, written by the OpenWrt project to support the small office and home office (SOHO) routers that the project is targeting. The main difference between swconfig and DSA is that DSA-supported switches show one network interface per port, whereas swconfig-configured switches show up as a single port, which limits the amount of information that can be extracted from the switch. For example, you cannot have per-port traffic statistics with swconfig. That limitation is what led to the creation of the switchdev framework, when swconfig was proposed (then refused) for inclusion in mainline. Another goal of switchdev was to support bridge hardware offloading and network interface card (NIC) virtualization. Also, whereas swconfig uses virtual LAN (VLAN) tagging to address ports, DSA enables the use of device-specific tagging headers to address different ports, which enables DSA to have better control over the switches. This allows, for example, DSA to do internet group management protocol (IGMP) snooping or implement the spanning tree protocol, whereas swconfig doesn't have those features. Some switches are actually connected to the host CPU through an Ethernet interface instead of regular PCI-Express interface, and DSA supports this as well. One advantage that remains in the swconfig approach is that it treats the internal switch as a simple external switch, and addresses ports with standard VLAN tags. This is something DSA could do, as well, but no one has bothered implementing this just yet. For now, DSA drivers use device-specific tagging mechanisms that limit the number of supported devices. Other areas of future improvement for DSA are better multi-chip support, IGMP snooping, and bonding, as well as firewall, NAT, and TC offloading.

Where is the freedom? Given all those technical improvements, you might rightfully wonder if your own wireless router or data center switch runs Linux. In recent years, we have seen more and more networking devices shipped with Linux and sometimes even OpenWrt (e.g. in the case of the Turris Omnia, which we previously covered), and especially on SOHO routers, but it sometimes means a crippled operating system that only offers you a proprietary web interface. But at least those efforts make it easier to deploy free operating systems on those devices. Based on my experience running OpenWrt on wireless routers to build the Montreal mesh network, deploying Linux on routers and switches has always been a manual process. The Ubiquiti hardware being used in the mesh network comes with an OpenWrt derivative, but it includes proprietary drivers and a proprietary web interface. To use the mesh networking protocol that was chosen, it was necessary to deploy custom OpenWrt images by hand. For years, it was a continuous struggle for OpenWrt developers to liberate generation after generation of proprietary hardware with companies like Cisco locking down the venerable WRT platform in 2006 and the US Federal Communications Commission (FCC) rules that forced TP-Link to block free software on its routers, a change that was later reverted. Most hardware providers are obviously not dedicated to software freedom: deploying Linux on their hardware is for them an economic, not political choice. As you might expect, a "Linux router" these days often means a closed device and operating system, using Linux as the only free component. I had the privilege of doing some reverse engineering on the SmartRG SR603n VDSL modem, which also doubles as a WiFi router and VoIP phone adapter. I was able to get a shell on that machine, and what I found was a custom operating system built on top of the Linux kernel. I wrote a detailed report about this two years ago and the situation then was pretty grim. Another experience I had was working over a decade in data centers, which tells an even worse story: most switches and routers there are not running free software at all. We have deployed HP ProCurve switches that provide free (as in beer) software updates and have struggled for years to find free (as in speech) software alternatives for those. We built our own routers using COTS server hardware, at a significant performance cost over the dedicated application-specific integrated circuits (ASICs) built into commercial routers, which do not offer us the trust and flexibility we were looking for. But Linux is definitely making some headway, and has been for a while. When we covered switchdev in February 2016, it was just getting started, but now vendors like Mellanox, Broadcom, Cumulus, and Intel are writing and shipping code using the framework. Cumulus, in particular, is developing a Debian-based distribution (Cumulus Linux) that it deploys for clients on targeted hardware. Most of the hardware in that list, however, is not actually open in the more radical sense: they are devices that can run free software but are not generally open-source hardware. There are some exceptions, but they sit at the higher end of the spectrum: most organizations probably don't need a 100 Gbps ports, let alone the 128 ports in the Backpack switch that Cumulus is shipping. How much this translates to actual freedom for the end-user is therefore questionable. While I have seen encouraging progress on the high end of the hardware spectrum at Netdev, I'm not sure this will translate into immediate wins in the data center or even for home users in the short term. In the long term, however, we will hopefully see some progress in Linux's rise in general-purpose networking hardware following its dominance in general-purpose computing.
The author would like to thank the Netdev organizers for travel assistance. Also, thanks to Andrew Lunn for a technical review of this article. Note: this article first appeared in the Linux Weekly News.

24 October 2016

Chris Lamb: Concorde

Today marks the 13th anniversary since the last passenger flight from New York arrived in the UK. Every seat was filled, a feat that had become increasingly rare for a plane that was a technological marvel but a commercial flop .




See also: A Rocket to Nowhere.

22 October 2016

Christoph Egger: Running Debian on the ClearFog

Back in August, I was looking for a Homeserver replacement. During FrOSCon I was then reminded of the Turris Omnia project by NIC.cz. The basic SoC (Marvel Armada 38x) seemed to be nice hand have decent mainline support (and, with the turris, users interested in keeping it working). Only I don't want any WIFI and I wasn't sure the standard case would be all that usefully. Fortunately, there's also a simple board available with the same SoC called ClearFog and so I got one of these (the Base version). With shipping and the SSD (the only 2242 M.2 SSD with 250 GiB I could find, a ADATA SP600) it slightly exceeds the budget but well. ClearFog with SSD When installing the machine, the obvious goal was to use mainline FOSS components only if possible. Fortunately there's mainline kernel support for the device as well as mainline U-Boot. First attempts to boot from a micro SD card did not work out at all, both with mainline U-Boot and the vendor version though. Turns out the eMMC version of the board does not support any micro SD cards at all, a fact that is documented but others failed to notice as well. U-Boot As the board does not come with any loader on eMMC and booting directly from M.2 requires removing some resistors from the board, the easiest way is using UART for booting. The vendor wiki has some shell script wrapping an included C fragment to feed U-Boot to the device but all that is really needed is U-Boot's kwboot utility. For some reason the SPL didn't properly detect UART booting on my device (wrong magic number) but patching the if (in arch-mvebu's spl.c) and always assume UART boot is an easy way around. The plan then was to boot a Debian armhf rootfs with a defconfig kernel from USB stick. and install U-Boot and the rootfs to eMMC from within that system. Unfortunately U-Boot seems to be unable to talk to the USB3 port so no kernel loading from there. One could probably make UART loading work but switching between screen for serial console and xmodem seemed somewhat fragile and I never got it working. However ethernet can be made to work, though you need to set eth1addr to eth3addr (or just the right one of these) in U-Boot, saveenv and reboot. After that TFTP works (but is somewhat slow). eMMC There's one last step required to allow U-Boot and Linux to access the eMMC. eMMC is wired to the same PINs as the SD card would be. However the SD card has an additional indicator pin showing whether a card is present. You might be lucky inserting a dummy card into the slot or go the clean route and remove the pin specification from the device tree.
--- a/arch/arm/dts/armada-388-clearfog.dts
+++ b/arch/arm/dts/armada-388-clearfog.dts
@@ -306,7 +307,6 @@
                        sdhci@d8000  
                                bus-width = <4>;
-                               cd-gpios = <&gpio0 20 GPIO_ACTIVE_LOW>;
                                no-1-8-v;
                                pinctrl-0 = <&clearfog_sdhci_pins
                                             &clearfog_sdhci_cd_pins>;
Next Up is flashing the U-Boot to eMMC. This seems to work with the vendor U-Boot but proves to be tricky with mainline. The fun part boils down to the fact that the boot firmware reads the first block from eMMC, but the second from SD card. If you write the mainline U-Boot, which was written and tested for SD card, to eMMC the SPL will try to load the main U-Boot starting from it's second sector from flash -- obviously resulting in garbage. This one took me several tries to figure out and made me read most of the SPL code for the device. The fix however is trivial (apart from the question on how to support all different variants from one codebase, which I'll leave to the U-Boot developers):
--- a/include/configs/clearfog.h
+++ b/include/configs/clearfog.h
@@ -143,8 +143,7 @@
 #define CONFIG_SPL_LIBDISK_SUPPORT
 #define CONFIG_SYS_MMC_U_BOOT_OFFS             (160 << 10)
 #define CONFIG_SYS_U_BOOT_OFFS                 CONFIG_SYS_MMC_U_BOOT_OFFS
-#define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR        ((CONFIG_SYS_U_BOOT_OFFS / 512)\
-                                                + 1)
+#define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR        (CONFIG_SYS_U_BOOT_OFFS / 512)
 #define CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS     ((512 << 10) / 512) /* 512KiB */
 #ifdef CONFIG_SPL_BUILD
 #define CONFIG_FIXED_SDHCI_ALIGNED_BUFFER      0x00180000      /* in SDRAM */
Linux Now we have a System booting from eMMC with mainline U-Boot (which is a most welcome speedup compared to the UART and TFTP combination from the beginning). Getting to fine-tune linux on the device -- we want to install the armmp Debian kernel and have it work. As all the drivers are build as modules for that kernel this also means initrd support. Funnily U-Boots bootz allows booting a plain vmlinux kernel but I couldn't get it to boot a plain initrd. Passing a uImage initrd and a normal kernel however works pretty well. Back when I first tried there were some modules missing and ethernet didn't work with the PHY driver built as a module. In the meantime the PHY problem was fixed in the Debian kernel and almost all modules already added. Ben then only added the USB3 module on my suggestion and as a result, unstable's armhf armmp kernel should work perfectly well on the device (you still need to patch the device tree similar to the patch above). Still missing is an updated flash-kernel to automatically generate the initrd uImage which is work in progress but got stalled until I fixed the U-Boot on eMMC problem and everything should be fine -- maybe get debian u-boot builds for that board. Pro versus Base The main difference so far between the Pro and the Base version of the ClearFog is the switch chip which is included on the Pro. The Base instead "just" has two gigabit ethernet ports and a SFP. Both, linux' and U-Boot's device tree are intended for the Pro version which makes on of the ethernet ports unusable (it tries to find the switch behind the ethernet port which isn't there). To get both ports working (or the one you settled on earlier) there's a second patch to the device tree (my version might be sub-optimal but works), U-Boot -- the linux-kernel version is a trivial adaption:
--- a/arch/arm/dts/armada-388-clearfog.dts
+++ b/arch/arm/dts/armada-388-clearfog.dts
@@ -89,13 +89,10 @@
                internal-regs  
                        ethernet@30000  
                                mac-address = [00 50 43 02 02 02];
+                               managed = "in-band-status";
+                               phy = <&phy1>;
                                phy-mode = "sgmii";
                                status = "okay";
-
-                               fixed-link  
-                                       speed = <1000>;
-                                       full-duplex;
-                                ;
                         ;
                        ethernet@34000  
@@ -227,6 +224,10 @@
                                pinctrl-0 = <&mdio_pins>;
                                pinctrl-names = "default";
+                               phy1: ethernet-phy@1   /* Marvell 88E1512 */
+                                    reg = <1>;
+                                ;
+
                                phy_dedicated: ethernet-phy@0  
                                        /*
                                         * Annoyingly, the marvell phy driver
@@ -386,62 +386,6 @@
                tx-fault-gpio = <&expander0 13 GPIO_ACTIVE_HIGH>;
         ;
-       dsa@0  
-               compatible = "marvell,dsa";
-               dsa,ethernet = <&eth1>;
-               dsa,mii-bus = <&mdio>;
-               pinctrl-0 = <&clearfog_dsa0_clk_pins &clearfog_dsa0_pins>;
-               pinctrl-names = "default";
-               #address-cells = <2>;
-               #size-cells = <0>;
-
-               switch@0  
-                       #address-cells = <1>;
-                       #size-cells = <0>;
-                       reg = <4 0>;
-
-                       port@0  
-                               reg = <0>;
-                               label = "lan1";
-                        ;
-
-                       port@1  
-                               reg = <1>;
-                               label = "lan2";
-                        ;
-
-                       port@2  
-                               reg = <2>;
-                               label = "lan3";
-                        ;
-
-                       port@3  
-                               reg = <3>;
-                               label = "lan4";
-                        ;
-
-                       port@4  
-                               reg = <4>;
-                               label = "lan5";
-                        ;
-
-                       port@5  
-                               reg = <5>;
-                               label = "cpu";
-                        ;
-
-                       port@6  
-                               /* 88E1512 external phy */
-                               reg = <6>;
-                               label = "lan6";
-                               fixed-link  
-                                       speed = <1000>;
-                                       full-duplex;
-                                ;
-                        ;
-                ;
-        ;
-
        gpio-keys  
                compatible = "gpio-keys";
                pinctrl-0 = <&rear_button_pins>;
Conclusion Apart from the mess with eMMC this seems to be a pretty nice device. It's now happily running with a M.2 SSD providing enough storage for now and still has a mSATA/mPCIe plug left for future journeys. It seems to be drawing around 5.5 Watts with SSD and one Ethernet connected while mostly idle and can feed around 500 Mb/s from disk over an encrypted ethernet connection which is, I guess, not too bad. My plans now include helping to finish flash-kernel support, creating a nice case and probably get it deployed. I might bring it to FOSDEM first though. Working on it was really quite some fun (apart from the frustrating parts finding the one-block-offset ..) and people were really helpful. Big thanks here to Debian's arm folks, Ben Hutchings the kernel maintainer and U-Boot upstream (especially Tom Rini and Stefan Roese)

22 July 2016

Martin Michlmayr: Debian on Seagate Personal Cloud and Seagate NAS

The majority of NAS devices supported in Debian are based on Marvell's Kirkwood platform. This platform is quite dated now and can only run Debian's armel port. Debian now supports the Seagate Personal Cloud and Seagate NAS devices. They are based on Marvell's Armada 370, a platform which can run Debian's armhf port. Unfortunately, even the Armada 370 is a bit dated now, so I would not recommend these devices for new purchases. If you have one already, however, you now have the option to run native Debian. There are some features I like about the Seagate NAS devices: If you have a Seagate Personal Cloud and Seagate NAS, you can follow the instructions on the Debian wiki. If Seagate releases more NAS devices on Marvell's Armada platform, I intend to add Debian support.

4 July 2016

Benjamin Mako Hill: Studying the relationship between remixing & learning

With more than 10 million users, the Scratch online community is the largest online community where kids learn to program. Since it was created, a central goal of the community has been to promote remixing the reworking and recombination of existing creative artifacts. As the video above shows, remixing programming projects in the current web-based version of Scratch is as easy is as clicking on the see inside button in a project web-page, and then clicking on the remix button in the web-based code editor. Today, close to 30% of projects on Scratch are remixes. Remixing plays such a central role in Scratch because its designers believed that remixing can play an important role in learning. After all, Scratch was designed first and foremost as a learning community with its roots in the Constructionist framework developed at MIT by Seymour Papert and his colleagues. The design of the Scratch online community was inspired by Papert s vision of a learning community similar to Brazilian Samba schools (Henry Jenkins writes about his experience of Samba schools in the context of Papert s vision here), and a comment Marvin Minsky made in 1984:
Adults worry a lot these days. Especially, they worry about how to make other people learn more about computers. They want to make us all computer-literate. Literacy means both reading and writing, but most books and courses about computers only tell you about writing programs. Worse, they only tell about commands and instructions and programming-language grammar rules. They hardly ever give examples. But real languages are more than words and grammar rules. There s also literature what people use the language for. No one ever learns a language from being told its grammar rules. We always start with stories about things that interest us.
In a new paper titled Remixing as a pathway to Computational Thinking that was recently published at the ACM Conference on Computer Supported Collaborative Work and Social Computing (CSCW) conference, we used a series of quantitative measures of online behavior to try to uncover evidence that might support the theory that remixing in Scratch is positively associated with learning. scratchblocksOf course, because Scratch is an informal environment with no set path for users, no lesson plan, and no quizzes, measuring learning is an open problem. In our study, we built on two different approaches to measure learning in Scratch. The first approach considers the number of distinct types of programming blocks available in Scratch that a user has used over her lifetime in Scratch (there are 120 in total) something that can be thought of as a block repertoire or vocabulary. This measure has been used to model informal learning in Scratch in an earlier study. Using this approach, we hypothesized that users who remix more will have a faster rate of growth for their code vocabulary. Controlling for a number of factors (e.g. age of user, the general level of activity) we found evidence of a small, but positive relationship between the number of remixes a user has shared and her block vocabulary as measured by the unique blocks she used in her non-remix projects. Intriguingly, we also found a strong association between the number of downloads by a user and her vocabulary growth. One interpretation is that this learning might also be associated with less active forms of appropriation, like the process of reading source code described by Minksy. The second approach we used considered specific concepts in programming, such as loops, or event-handling. To measure this, we utilized a mapping of Scratch blocks to key programming concepts found in this paper by Karen Brennan and Mitchel Resnick. For example, in the image below are all the Scratch blocks mapped to the concept of loop . scratchblocksctWe looked at six concepts in total (conditionals, data, events, loops, operators, and parallelism). In each case, we hypothesized that if someone has had never used a given concept before, they would be more likely to use that concept after encountering it while remixing an existing project. Using this second approach, we found that users who had never used a concept were more likely to do so if they had been exposed to the concept through remixing. Although some concepts were more widely used than others, we found a positive relationship between concept use and exposure through remixing for each of the six concepts. We found that this relationship was true even if we ignored obvious examples of cutting and pasting of blocks of code. In all of these models, we found what we believe is evidence of learning through remixing. Of course, there are many limitations in this work. What we found are all positive correlations we do not know if these relationships are causal. Moreover, our measures do not really tell us whether someone has understood the usage of a given block or programming concept.However, even with these limitations, we are excited by the results of our work, and we plan to build on what we have. Our next steps include developing and utilizing better measures of learning, as well as looking at other methods of appropriation like viewing the source code of a project.

This blog post and the paper it describes are collaborative work with Sayamindu Dasgupta, Andr s Monroy-Hern ndez, and William Hale. The paper is released as open access so anyone can read the entire paper here. This blog post was also posted on Sayamindu Dasgupta s blog and on Medium by the MIT Media Lab.

1 March 2016

Russ Allbery: Review: The Lost Steersman

Review: The Lost Steersman, by Rosemary Kirstein
Series: Steerswomen #3
Publisher: Rosemary Kirstein
Copyright: 2003, 2014
Printing: 2014
ISBN: 0-9913546-2-1
Format: Kindle
Pages: 432
This is the third book in the Steerswomen series and a direct follow-up to the events of The Outskirter's Secret. It does, marvel of marvels, feature an in-character summary of the events of the series to date! I do love when authors do this; it helps immensely if you come back to a series after a bit of a break between books. But this whole series is so good, and the emotional tone and development of Rowan as a character is so strong, that I recommend against starting here. After the events of the last book, Rowan has returned to the Inner Lands. She's sent her report back to the Archives, but stopped at the Annex in Alemeth. This is an auxiliary library that should have copies of the journals and other research that Rowan wants to search, and stopping there saves substantial travel time. However, she finds the steerswoman who was custodian of the Annex is deceased and the Annex is, from Rowan's perspective, a mess. Nothing is organized, the books aren't properly cared-for, and Mira's interactions with the townsfolk were far different than Rowan's natural attitude. The start of this book was a surprising shift. After the large-scale revelations at the end of The Outskirter's Secret, and the sense of escalating danger, Rowan's return to small-town life in the Inner Lands comes as a shock. That's true for both the reader and for Rowan, and the parallels make it a remarkably effective bit of writing. At the beginning of the story, the reader is already familiar with Rowan (at least if you've read the previous books) and how she thinks of being a steerswoman. Rowan is very much on edge and in a hurry given what's going on in the broader world. But the town is used to Mira: a gregarious socializer who cared far more about town gossip and her role as coordinator of it than she cared about most of her steerswoman duties. (At least as seen from Rowan's perspective. By the end of the book, we have a few hints that something else might be going on, but the damage to the books at least feels unforgivable.) Rowan is resented and even disliked at first, particularly by Steffie and Gwen who did most of the chores at the Annex and were closest to Mira. One of the reasons why I love this series so much is that Kirstein has a gift for characterization. Rowan (and Bel, who largely doesn't appear in this book) are brilliant characters, but it's not just them. At the start of this book, the reader tends to share Rowan's opinion of the town: a sort of half-bemused, half-exasperated indifference. Even as the characters start to grow on one, it seems like a backwater and a diversion from the larger story. But it becomes clear that Rowan is very on-edge from her experience in the Outskirts, that she's underestimated the relevance of Mira to at least the town's happiness, and she's greatly underestimated the ability of the townsfolk to help her. Steffie, in particular, is a wonderful character; by the end of the book, he had become one of my favorite people in the series so far. He doesn't think he's particularly smart, and his life before Rowan is very simple, but there are depths to him that no one, including him, expected. There is a plot here, apart from small town politics and Rowan's slow relaxation. (Although those were so compelling that I'm not sure I would have minded if that were the entire book.) The lost steersman of the title is an old student friend of Rowan that she unexpectedly meets in town, a former steersman who quit the order and refused to explain why. Rowan, of course, cannot resist trying to fix this situation. The second plot driver is a dangerous invasion of Outskirts monsters into the town. Those who have read the previous books will have some immediate guesses as to why this might be, and Rowan does as well. But there's more going on than it might first appear. This book is not entirely a diversion. It returns to the main plot of the series by the end of the book, and we learn much more about Rowan's world. But, somewhat surprisingly, that was my least favorite part of the book. It has some nice bits of exploration and puzzle-solving, and Rowan is always a delight to spend time with. But the last section of the book is similar to many other genre books I've read before well-written, to be sure, but not as unique. It also features a rather long section following a character who is severely physically ill, which is something I always find very hard to read (a personal quirk). But there's a lot of meat here for the broader plot, and I have no idea what will happen in the next book. The part of The Lost Steersman that I'm going to remember, though, are the town bits, up through the arrival of Zenna (another delightful character who adds even more variety to Kirstein's presentation of steerswomen). Kirstein is remarkably good at mixing small-town characters with the scientific investigation of the steerswomen and letting them bounce off of each other to reveal more about the character of both. If it weren't for the end of the book, which bothered me for partly idiosyncratic reasons, I think this would have been my favorite book of the series. Followed by The Language of Power, and be warned that this book ends on something close to a cliffhanger. Rating: 8 out of 10

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