turn off VDSO on glibc side

heroxbd heroxbd@gentoo.org
Wed Jul 3 08:06:00 GMT 2013


Hey Mike,

Good to see you! I'm on list, so no need to Cc me.

Mike Frysinger <vapier@gentoo.org> writes:

> there aren't any configure flags or runtime knobs that i know of on
> the glibc side of things.  you could edit elf/dl-support.c and try
> commenting out the parts that handle AT_SYSINFO and AT_SYSINFO_EHDR.
> or edit sysdeps/unix/sysv/linux/x86_64/gettimeofday.c and force it to
> always use the syscall version at the end of the file.

Mike, you rock! It would take me hours or days to find out the right
place to hack. Thanks a lot.

Expecting it to be easier, I tried the second approach, gcc bootstrapped
happily. But the problem remains for clock_gettime, used by patch,
failing in the same pattern. I am afraid I have to disable vdso
completely for this kernel, not only part of functions it provides, in
order not to have my system crash in later unexpected places.

More on that later on the first apprach.

> or upgrade your kernel to one that isn't buggy :p

Yeah. At the same time, RHEL is our main use case for Prefix/libc where
glibc is too old. I think doing the patch on our side is better than
getting users to upgrade their already-set-up-but-easy-to-break or
hard-to-request-kernel-upgrade-VPS systems.

Cheers,
Benda
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