[Python-Dev] ia64 debian buildbot (original) (raw)

Thomas Heller theller at python.net
Thu Apr 13 22:02:19 CEST 2006

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

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