linux-kernel - Re: kdump, ia64: always reserve elfcore header memory in crash kernel

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Date:	Wed, 6 Aug 2008 09:47:58 +1000
From:	Simon Horman <horms@...ge.net.au>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	kexec@...ts.infradead.org, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: kdump, ia64: always reserve elfcore header memory in crash
	kernel

On Tue, Aug 05, 2008 at 08:56:34AM -0400, Vivek Goyal wrote:
> On Tue, Aug 05, 2008 at 07:48:27PM +1000, Simon Horman wrote:
> > elfcore header memory needs to be reserved in a crash kernel.
> > This means that the relevant code should be protected
> > by CONFIG_CRASH_DUMP rather than CONFIG_PROC_VMCORE.
> > 
> > Signed-off-by: Simon Horman <horms@...ge.net.au>
> > 
> > --- 
> > Andrew, this patch fixes bug in the (unlikely) case where
> > an ia64 crashdump kernel does not have CONFIG_PROC_FS set.
> > I think it is worth including in 2.6.27. But breakage cases are
> > likely to be minimal to non-existent, so I am comfortable
> > with post 2.6.27 too.
> > 
> > This patch should be appended to the series,
> > "is_kdump_kernel() cleanup and related patches".
> > 
> > http://lists.infradead.org/pipermail/kexec/2008-July/002270.html
> > 
> > Index: linux-2.6/arch/ia64/kernel/efi.c
> > ===================================================================
> > --- linux-2.6.orig/arch/ia64/kernel/efi.c	2008-08-05 18:31:13.000000000 +1000
> > +++ linux-2.6/arch/ia64/kernel/efi.c	2008-08-05 18:31:21.000000000 +1000
> > @@ -1334,7 +1334,7 @@ kdump_find_rsvd_region (unsigned long si
> >  }
> >  #endif
> >  
> > -#ifdef CONFIG_PROC_VMCORE
> > +#ifdef CONFIG_CRASH_DUMP
> >  /* locate the size find a the descriptor at a certain address */
> >  unsigned long __init
> >  vmcore_find_descriptor_size (unsigned long address)
> > Index: linux-2.6/arch/ia64/kernel/setup.c
> > ===================================================================
> > --- linux-2.6.orig/arch/ia64/kernel/setup.c	2008-08-05 18:31:20.000000000 +1000
> > +++ linux-2.6/arch/ia64/kernel/setup.c	2008-08-05 18:31:21.000000000 +1000
> > @@ -352,7 +352,7 @@ reserve_memory (void)
> >  	}
> >  #endif
> >  
> > -#ifdef CONFIG_PROC_VMCORE
> > +#ifdef CONFIG_CRASH_KERNEL
> >  	if (reserve_elfcorehdr(&rsvd_region[n].start,
> >  			       &rsvd_region[n].end) == 0)
> >  		n++;
> 
> Hi Simon,
> 
> Thanks for the patch. One minor nit. I think compilation will fail
> in the case of CONFIG_PROC_VMCORE=n. Because reserve_elfcorehdr will
> try to use vmcore_unusabe() which is not available now?

Yes, sorry. I forgot to send a revised version of the patch that
creates vmcore_unusabe() so that it is present if CONFIG_PROC_VMCORE=n.
I will do so.

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