[Python-Dev] ia64 debian buildbot

[Thomas Heller]

Martin v. Löwis wrote:
> Thomas Heller wrote:
>> Why does the ia64 debian buildbot now complain about unaligned accesses,
>> and how can we find out where they occur?
> 
> I don't know why they started show up suddenly; on Debian-Itanium, it
> is a configuration option (even per process, through prctl(1)) whether
> they just produce a log message, or a signal, or nothing; if they
> produce a log message, this also goes to the process' terminal.
> 
> These unaligned access must have been there for some time now;
> perhaps something on the machine has changed. Matthias?
> 
> Finding where they originate from is really hard. You need to
> set the process into the "signal unaligned access" mode, and
> then run it under a debugger, so you know where it crashes.
> This requires shell access to the machine.
> 
> I have tried to reproduce it on my Itanium machine, and found that
> that they come from the AST compiler's arena (I /knew/ it was
> wrong to implement your own memory management algorithms :-): it
> was returning memory blocks that were only 4-aligned, so the
> the pointers in the ASDL sequences were all unaligned; hence the
> errors.
> 
> I changed that to always guarantee 8-alignment for all blocks
> returned from the arena; that seems to help.

Cool - thanks. I'm anxiously waiting until the buildbot runs the ctypes-test ;-).

Thomas