Messages in this thread | | | Date | Thu, 20 Aug 2009 12:59:46 +0200 | From | Takashi Iwai <> | Subject | Re: [REGRESSION] _end symbol missing from Symbol.map |
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At Thu, 20 Aug 2009 07:59:26 +0200, Hannes Reinecke wrote: > > Andrew Morton wrote: > > On Thu, 13 Aug 2009 08:45:20 +0200 Hannes Reinecke <hare@suse.de> wrote: > > > >> Hi all, > >> > >> with 2.6.31 'crash' on x86_64 falls flat on its face as the '_end' symbol > >> is missing from the System.map file. > >> > >> The culprit is commit 091e52c3551d3031343df24b573b770b4c6c72b6, > >> which moved the '_end' symbol into it's own section. > >> Apparently this causes kallsyms to not reference it properly. > >> > >> So either we'd need to revert part of the patch to not > >> include _end in it's own section: > >> > >> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S > >> index 59f31d2..1422df5 100644 > >> --- a/arch/x86/kernel/vmlinux.lds.S > >> +++ b/arch/x86/kernel/vmlinux.lds.S > >> @@ -376,9 +376,7 @@ SECTIONS > >> __brk_limit = .; > >> } > >> > >> - .end : AT(ADDR(.end) - LOAD_OFFSET) { > >> - _end = .; > >> - } > >> + _end = .; > >> > >> /* Sections to be discarded */ > >> /DISCARD/ : { > >> > >> or someone has to fixup kallsyms. But this is far beyond my comfort zone. > >> > > > > So System.map is part of the kernel API too? Sigh. > > > > Your email client replaces tabs with spaces. > > > I know. > > > The patch didn't have a signed-off-by: > > > I know, too. > However, this is clearly a band-aid, and as such I reported > it more as an RFC. > One (Sam?) should really fix up kallsyms to extract the _end symbol. > Hence I didn't warrant it with a Signed-off line. > > > I queued it up, and tagged it for -stable backporting. Unless we come > > up with something better. > > > I was sort of hoping Sam would speak up and present some better approach ... > > > We might not get this into 2.6.31, in which case this fix or its > > replacement will need backporting to 2.6.30.x and 2.6.31.x (IMO).
Yep, x86-32 had already the own end section in 2.6.30 kernel, which was introduced by the following commit:
commit 0a699af8e613a670be50245366fa18cb19ac5172 Author: H. Peter Anvin <hpa@linux.intel.com> Date: Tue Mar 17 14:14:31 2009 -0700
x86-32: move _end to a dummy section
Impact: build fix with CONFIG_RELOCATABLE
Move _end into a dummy section, so that relocs.c will know it is a relocatable symbol.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org>
So, judging from the commit log, simply reverting it seems to have some drawback...?
thanks,
Takashi
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