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From: Andi Kleen <ak@suse.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] sysctl: Allow /proc/sys without sys_sysctl
Date: Wed, 12 Jul 2006 15:32:05 +0200
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On Wednesday 12 July 2006 05:13, Eric W. Biederman wrote:
> Andi Kleen <ak@suse.de> writes:
> > ebiederm@xmission.com (Eric W. Biederman) writes:
> >> Since sys_sysctl is deprecated start allow it to be compiled out.
> >> This should catch any remaining user space code that cares,
> >
> > I tried this long ago, but found that glibc uses sysctl in each
> > program to get the kernel version. It probably handles ENOSYS,
> > but there might be slowdowns or subtle problems from it not knowing
> > the kernel version.
> >
> > So I think it's ok to remove the big sysctl, but at a very minimal
> > replacement that just handles (CTL_KERN, KERN_VERSION) is needed.
>
> If glibc is looking at kernel.osrelease it might make sense.
> If glibc is looking at kernel.version which is just the build number
> and date I can't imagine a correct usage.

It's KERN_VERSION 

>>From my /bin/ls:

_sysctl({{CTL_KERN, KERN_VERSION}, 2, 0xbfc8e1e0, 30, (nil), 0}) = 0

> If this usage is still common in glibc we can decide what to do
> when the warnings pop up.

printk for everything would annoy basically everybody. Not a good idea.

-Andi