linux-kernel - Re: [REGRESSION] Recent change to kernel spikes out ccache/distcc

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Message-Id: <4964CA0A.76E4.0078.0@novell.com>
Date:	Wed, 07 Jan 2009 14:28:10 +0000
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	"Al Viro" <viro@...IV.linux.org.uk>
Cc:	<ccache@...ts.samba.org>, "Theodore Ts'o" <tytso@....edu>,
	"Sam Ravnborg" <sam@...nborg.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [REGRESSION] Recent change to kernel spikes out
	 ccache/distcc

>>> Al Viro <viro@...IV.linux.org.uk> 07.01.09 15:03 >>>
>I do not understand two things.
>	a) WTF would we care about ones in vmlinux, when kallsyms drops the
>absolute ones anyway?

The patch is not only about __crc_* - for vmlinux, this part really doesn't
matter, but there's a significant amount of other symbols that get stripped
from vmlinux with the second patch.

>	b) is there any reason why we can't copy symbol table out of module
>ourselves (instead of setting SHF_ALLOC on it) and trim the crap out of
>it?  Note that __crc_... is not the only junk in there - you don't need
>(or want) to keep the things like undefs for /proc/kallsyms purposes.
>And modules *using* an exported symbol are more common that modules exporting
>one...  Why not copy it at add_kallsyms() time, skipping the junk we don't
>want anyway?

Would certainly be doable, but would seem reasonable only if it's a small
set of easily recognizable symbols. If you look at scripts/strip-symbols,
you may agree that it's better to do this at build time...

Jan

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