From: Neil Horman <nhorman@redhat.com>
Subject: Re: [RHEL 5.1 PATCH] Fix regression in x86_64 kexec
Date: Thu, 14 Jun 2007 07:10:25 -0400
Bugzilla: 242648
Message-Id: <20070614111025.GD7150@hmsendeavour.rdu.redhat.com>
Changelog: [x86_64] Fix regression in kexec


> On Wed, Jun 06, 2007 at 02:33:48PM -0400, Neil Horman wrote:
> > Hey-
> > 	RHEL5 x86_64 kernels have a kexec regression stemming from some
> > crashkernel parameter bounds checking that got added in -14.  Nominally we
> > validate the crashkernel reserved memory size and location against max_low_pfn
> > and min_low_pfn, which works great on x86 systems.  However on x86_64 systems,
> > max_low_pfn and min_low_pfn are not initalized, and so the check fails
> > regardless of the values specified for the crashkernel parameter.  On x86_64,
> > since we should be able to use any physically present memory as reserved space
> > for kexec, we should be validating against end_pfn rather than max_low_pfn to
> > ensure that we are reserving physically present RAM.  This is a repo patch
> > against linux-2.6-kdump-bounds-checking-for-crashkernel-args.patch to correct
> > this.  I've tested it on my x86_64 system here and it works fine.  Fixes bz
> > 242648.
> 

--- linux-2.6.18.noarch/arch/x86_64/kernel/setup.c.kexec	2007-06-14 07:05:56.000000000 -0400
+++ linux-2.6.18.noarch/arch/x86_64/kernel/setup.c	2007-06-14 07:06:05.000000000 -0400
@@ -641,7 +641,7 @@
 #endif
 #ifdef CONFIG_KEXEC
 	if ((crashk_res.start < crashk_res.end) &&
-	    (crashk_res.end <= (max_low_pfn << PAGE_SHIFT))) {
+	    (crashk_res.end <= (end_pfn << PAGE_SHIFT))) {
 		reserve_bootmem_generic(crashk_res.start,
 					crashk_res.end - crashk_res.start + 1);
 	}
--- linux-2.6.18.noarch/arch/x86_64/kernel/setup-xen.c.kexec	2007-06-14 07:06:13.000000000 -0400
+++ linux-2.6.18.noarch/arch/x86_64/kernel/setup-xen.c	2007-06-14 07:06:37.000000000 -0400
@@ -759,7 +759,7 @@
 #endif	/* !CONFIG_XEN */
 #ifdef CONFIG_KEXEC
 	if ((crashk_res.start < crashk_res.end) &&
-	    (crashk_res.end <= (max_low_pfn << PAGE_SHIFT))) {
+	    (crashk_res.end <= (end_pfn << PAGE_SHIFT))) {
 		reserve_bootmem_generic(crashk_res.start,
 					crashk_res.end - crashk_res.start + 1);
 	}
-- 
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 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman@redhat.com
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 *http://pgp.mit.edu
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