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Re: Linux kernel headers


Ryan Arnold wrote:
On Thu, Jul 2, 2009 at 8:06 AM, Petr Baudis<pasky@suse.cz> wrote:
Actually, it's the other way around I think.

--enable-kernel is the _minimal_ version glibc supports. It means that
it assumes that features present in this kernel version are present and
it does not waste cycles checking their presence and having
compatibility code compiled in. So, if you specify 2.6.30, your glibc
may not work with 2.6.29, but if you specify 2.6.29, your glibc will
certainly work with 2.6.30 (albeit slightly less efficiently in theory).

Yes you're right.. I can't believe I got this wrong considering how long I worked with the ill-fated *context routines for PowerPC.

I actually plan to do some benchmarks on how various settings affect
this since for historical reasons, in SUSE we still use
--enable-kernel=2.6.4. If you know about any existing benchmarks,
I would appreciate that. :-)

There are two big features that I can think of that may demonstrate marked improvement.

Private Futex support and Per Thread Malloc Arena (i.e. experimental malloc).

Lack of accessible benchmarks certainly seems to be an issue.

Ryan

This is probably why I received a segmentation fault.
i.g. compiled originally with --enable-kernel=2.6.0
but then later on left that option out, now
with the segmentation fault I remember
doing --enable-kernel=2.6.31

luckily the system is recoverable if this occurs.

Justin P. Mattock


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