Re: [PATCH] Use uname not sysctl to get the kernel revision

[ebiederm@xmission.com (Eric W. Biederman)]

"H. Peter Anvin" <hpa@zytor.com> writes:

> Jakub Jelinek wrote:
>> On Wed, Jul 12, 2006 at 12:33:56PM -0700, Ulrich Drepper wrote:
>>> Roland McGrath wrote:
>>>> We could also put the uname info (modulo nodename) into the vDSO.
>>> Or even better: real topology information.
>> AND rather than OR would be even better.  So glibc could find kernel
>> version, etc. and topology in the vDSO cheaply.
>
> Wouldn't it make more sense for this to be in ELF tags, rather than the vdso?
> Another alternative, I guess, would be to put a pointer in the ELF tags, which
> may point into the vdso.

Cheap and simple access to topology information would be interesting.

Glibc just wants to know if our kernel is SMP so it can know if it is
ok to busy wait for a bit waiting for a mutex.  Or if busy waiting is
a complete loss.

The practical challenge is that topology information is not fixed but
potentially varies at runtime.

Ulrich what would be interesting besides the possibility of having
multiple cpus?

Eric