Subject: Re: [PATCH 0/59] Cleanup sysctl

From: "H. Peter Anvin" <[email-masked]>
Date: Tue, 16 Jan 2007 08:53:19 -0800

Eric W. Biederman wrote:
> 
> - Removal of sys_sysctl support where people had used conflicting sysctl
>   numbers. Trying to break glibc or other applications by changing the
>   ABI is not cool.  9 instances of this in the kernel seems a little
>   extreme.
> 

It would be highly advantageous if we could have a file that acts as a 
central registry of architectural sysctl numbers *and have the numbers 
in the kernel derived from there*.  As I've said before, I don't really 
think sys_sysctl is any worse than ad hoc system calls (sys_mips and the 
like), but the real problem is that there are architectural and 
non-archtectural numbers, and they're mixed in all over the place.

I think it would be fair to say that if they're not in <linux/sysctl.h> 
they're not architectural, but that doesn't resolve the counterpositive 
(are there sysctls in <linux/sysctl.h> which aren't architectural?  From 
the looks of it, I would say yes.)  Non-architectural sysctl numbers 
should not be exported to userspace, and should eventually be rejected 
by sys_sysctl.

	-hpa