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Re: Bug in memset() causing quake3 to crash.
From: |
Andreas Jaeger |
Subject: |
Re: Bug in memset() causing quake3 to crash. |
Date: |
Tue, 16 Oct 2001 12:02:50 +0200 |
User-agent: |
Gnus/5.090004 (Oort Gnus v0.04) XEmacs/21.4 (Artificial Intelligence) |
Ulrich Drepper <address@hidden> writes:
> Han <address@hidden> writes:
>
>> Hello,
>>
>> In recent versions of the kernel a bug apeared which caused quake3 to
>> segfault during startup. It was discussed on this mailing list and
>> recognized by Alan Cox:
>>
>> http://opensource.creative.com/pipermail/emu10k1-devel/2001-September/004884.html
>
> There is no desription of a problem. And there will be no bug found
> in memset. It's most definitely just another incapable programmer who
> assumes that memory can be write-only.
The report reads:
aha. I solved the quake issue. so, quake3 mmap()'s the sound device with
PROT_WRITE, then calls memset(mem, 0, size) .. and on the i586 and i686 the
memset() routine in glibc (I'm using redhat's .i686.rpm glibc rpm) does
a read on the memory because of caching issues. This was fixed by doing an
LD_PRELOAD of a little dummy memset.so containing a simple C implementation
of memset(). The bug has been reported to the iD linux people.
And therefore I agree with Ulrich - the memory cannot be write-only.
Andreas
--
Andreas Jaeger
SuSE Labs address@hidden
private address@hidden
http://www.suse.de/~aj