linux-kernel - Re: [PATCH 1/1] Allow i386 crash kernels to handle x86

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Message-ID: <20070315014635.GC28396@verge.net.au>
Date:	Thu, 15 Mar 2007 10:46:38 +0900
From:	Horms <horms@...ge.net.au>
To:	Ian Campbell <Ian.Campbell@...Source.com>
Cc:	vgoyal@...ibm.com, hbabu@...ibm.com, fastboot@...ts.osdl.org,
	linux-kernel@...r.kernel.org, Magnus Damm <magnus.damm@...il.com>
Subject: Re: [PATCH 1/1] Allow i386 crash kernels to handle x86_64 dumps

On Wed, Mar 14, 2007 at 05:00:09PM +0000, Ian Campbell wrote:
> The specific case I am encountering is kdump under Xen with a 64 bit
> hypervisor and 32 bit kernel/userspace. The dump created is a 64 bit due
> to the hypervisor but the dump kernel is 32 bit to match the domain 0
> kernel.
> 
> It's possibly less likely to be useful in a purely native scenario but I
> see no reason to disallow it.

For native Linux, would this cover the case where the pre-crash kernel
is 64bit and the crashdump (post-crash) kernel is 32bit?

> Signed-off-by: Ian Campbell <ian.campbell@...source.com>
> 
> --- pristine-linux-2.6.18/include/asm-i386/elf.h	2006-09-20 04:42:06.000000000 +0100
> +++ linux-2.6.18-xen/include/asm-i386/elf.h	2007-03-14 16:42:30.000000000 +0000
> @@ -36,7 +36,7 @@
>   * This is used to ensure we don't load something for the wrong architecture.
>   */
>  #define elf_check_arch(x) \
> -	(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486))
> +	(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486) || ((x)->e_machine == EM_X86_64))

I think it would be a bit nicer if this was < 80col wide,
though obviously this doesn't affect the funtionality.

diff --git a/include/asm-i386/elf.h b/include/asm-i386/elf.h
index 8d33c9b..cd894dd 100644
--- a/include/asm-i386/elf.h
+++ b/include/asm-i386/elf.h
@@ -36,7 +36,8 @@ typedef struct user_fxsr_struct elf_fpxregset_t;
  * This is used to ensure we don't load something for the wrong architecture.
  */
 #define elf_check_arch(x) \
-	(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486))
+	(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486) || \
+	 ((x)->e_machine == EM_X86_64))
 
 /*
  * These are used to set parameters in the core dumps.
-
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