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Sergei Trofimovich
Worked at VirusBlokAda Ltd.
Attended Belarusian State University
Lives in Minsk
109 followers|24,783 views
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Sergei Trofimovich

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As it turns out, old technology scales pretty well.
Why ? - short answer : Because I want to. Why ? - long answer : Computers are quite opaque, looking at them it's impossible to see how they work. What I would like to do is get inside and see what's going on. Trouble is we can't shrink down small enough to walk inside a silicon chip.
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Sergei Trofimovich

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Erik de Castro Lopo's profile photo
 
Yeah, that was some really good work by +Neil Mitchell !
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Sergei Trofimovich

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Ever wondered how 'perf top' looks on haskell programs?

Something like that: http://trofi.github.io/posts/192-perf-on-haskell-programs.html
perf on haskell programs. GHC 7.10.1 got a new -g option to generate debugging information in DWARF format for compiled haskell code. While the -g option was being developed I asked Peter a few times on #ghc how perf top would look like for a random haskell program.
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Erik de Castro Lopo's profile photo
 
This is really interesting +Sergei Trofimovich. I hope there's some patches for GHC coming :).
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Sergei Trofimovich

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Another weekend, another lotz of funz. Guest start is m68k:

http://trofi.github.io/posts/191-ghc-on-m68k.html

GHC on m68k. This all started from this ghc bug report. The bug stated that on m68k ABI return values of int-type are passed in register %d0 while void *-type are passed in register %a0. GHC's C codegen was not using return types consistently. I had zero knowledge of m68k at that time.
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Erik de Castro Lopo's profile photo
 
That's somre really cool hacking Sergi. Congrats!
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Sergei Trofimovich

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PR other/60465 * config/ia64/ia64.c (ia64_expand_load_address): Use gprel64 for local symbolic operands. * config/ia64/predicates.md (local_symbolic_operand64): New predicate. PR othe...
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Ondřej Súkup's profile photoSergei Trofimovich's profile photoАндрэй Захарэвіч's profile photo
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Віншую!
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Sergei Trofimovich

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Yes, there is now a "fake" short fingerprint for my kernel signing key out there on the key servers, and yes, it's not really mine, and yes, we know who did it, and yes, it's revoked, and no, it wasn't just targeted at kernel developers, but at all 24000 keys in the "strong" ring of PGP trust, and yes something like this has been possible for a very long time now so it's not really that much news, and yes, gpg really is horrible to use and almost impossible to use correctly.

See the top comment here for more details:
https://news.ycombinator.com/item?id=12296974

And of course, read the evil32.com site for loads of details.

I guess I should be happy that people are checking the signature of my kernel releases, and emailing me that something is "wrong" on their system, that's nice to see. Too bad their scripts are "wrong" as they pull in all keys with a possible 32bit signature and things go boom.

Short answer, always use "long" keys when using gpg, and never auto-refresh keys from the keyservers.
GPG usage has grown steadily while the tooling that supports it remains stagnant despite staggering hardware advancement. 32bit key ids were reasonable 15 years ago but are obsolete now. Using modern GPUs, we have found collisions for every 32bit key id in the WOT's (Web of Trust) strong set.
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Sergei Trofimovich

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Last weekend was fun: I've spent some time to unbreak pulseaudio on my machine:
    https://bugs.freedesktop.org/show_bug.cgi?id=96873

I happen to use PA over TCP on fresh git kernels. Kernel slightly changed sendmsg()  to be more strict. It started rejecting SCM_CREDENTIALS control message on TCP sockets (pulseaudio wart)

Usermode linux and it's hostfs mount are ideal to validate and bisech that sort of bugs.without any disruption to host kernel.

The proper fix appeared a few hour later I've send an email to kernel devs. And it was Sunday. Amazing!

The fix:
    https://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=779f1edec664a7b32b71f7b4702e085a08d60592
Noticed breakage on real applications like mpv and other media apps. PA used to work but I'm not sure what exactly changed in my environment. Currently pulseaudio over TCP is broken on the following versions: 7.1, 8.0, 9.0. How to reproduce: ================= 1. run pulseaudio server on one ...
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Sergei Trofimovich

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Disclaimers, et al. These opinions are not at all related to Arch Linux, though maintaining Arch packages has certainly colored my opinions. I've been a volunteer maintainer for years now, because I feel it helps people. I have a bias towards the value that maintainers and maintaining packages ...
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Sergei Trofimovich

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An update on my 2014 report.
New GCC is just around the corner. For me, as a GCC developer, this means a period of bugfixing, benchmarking and fine-tuning. Two years ago I wrote about my experiment of building libreoffice with link time optimization (LT...
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Sergei Trofimovich

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Add flag to optionally ignore ELF interposition. From: Jan Hubicka ; To: gcc-patches at gcc dot gnu dot org; Date: Tue, 20 May 2014 22:04:32 +0200; Subject: Add flag to optionally ignore ELF interposition; Authentication-results: sourceware.org; auth=none ...
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Sergei Trofimovich

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glibc on ia64 or how relocations bootstrap. It was a rainy evening on #gentoo-ia64 and suddenly 00:40 < undersys> trying out glibc 2.21 on my ia64 box 00:41 < undersys> all compiles fine, gets to preinstall test and fails 00:41 < undersys> "simple run test (/usr/bin/cal) failed" wat :C ..
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Lennart Kolmodin's profile photo
 
Interesting read, hairy horror story :)
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Tagline
bit master
Introduction
gentoo, haskell, c, exotic arches, natural languages.
snowboarding, (folk) music and more!
Education
  • Belarusian State University
    Radiophysics, 2002 - 2007
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Employment
  • VirusBlokAda Ltd.
    Very Serious Guy, 2006 - 2014
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Minsk
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Zhodino