[PATCH v3] x86: UV kdump reboot fix

[PATCH v3] x86: UV kdump reboot fix

[Cliff Wickman]

From: Cliff Wickman <cpw@sgi.com>

After a crash dump on an SGI Altix UV system the crash kernel fails to
cause a reboot.  EFI mode is disabled in the kdump kernel, so only the
reboot_type of BOOT_ACPI works.

> The clean solution would be to add the reboot_type setting to an UV specific
> initialization function. That way only UV is affected and there's no extra
> kludge either, as reboot_type is already global.  [Ingo]
(this is too simple -- sometimes I can't see the forest for the trees!)

Diffed against 2.6.38-rc8 (current tip tree)

Signed-off-by: Cliff Wickman <cpw@sgi.com>

 arch/x86/kernel/apic/x2apic_uv_x.c |    9 +++++++++
 1 file changed, 9 insertions(+)

Index: linux.trees.git/arch/x86/kernel/apic/x2apic_uv_x.c
===================================================================
--- linux.trees.git.orig/arch/x86/kernel/apic/x2apic_uv_x.c
+++ linux.trees.git/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -23,6 +23,7 @@
 #include <linux/io.h>
 #include <linux/pci.h>
 #include <linux/kdebug.h>
+#include <linux/crash_dump.h>
 
 #include <asm/uv/uv_mmrs.h>
 #include <asm/uv/uv_hub.h>
@@ -34,6 +35,7 @@
 #include <asm/ipi.h>
 #include <asm/smp.h>
 #include <asm/x86_init.h>
+#include <asm/emergency-restart.h>
 
 DEFINE_PER_CPU(int, x2apic_extra_bits);
 
@@ -810,4 +812,11 @@ void __init uv_system_init(void)
 
 	/* register Legacy VGA I/O redirection handler */
 	pci_register_set_vga_state(uv_set_vga_state);
+
+	/*
+	 * for a kdump kernel the reset must be BOOT_ACPI, not BOOT_EFI, as
+	 * EFI is not enabled in the kdump kernel.
+	 */
+	if (is_kdump_kernel())
+		reboot_type = BOOT_ACPI;
 }

Re: [PATCH v3] x86: UV kdump reboot fix

[Ingo Molnar]

* Cliff Wickman <cpw@sgi.com> wrote:

> Diffed against 2.6.38-rc8 (current tip tree)

It does not apply here:

patching file arch/x86/kernel/apic/x2apic_uv_x.c
Hunk #1 FAILED at 23.
Hunk #2 succeeded at 35 (offset 1 line).
Hunk #3 succeeded at 812 (offset 1 line).
1 out of 3 hunks FAILED -- rejects in file arch/x86/kernel/apic/x2apic_uv_x.c

But yeah, the patch looks good now.

One minor nit, please watch out for the proper capitalization of sentences:

> +
> +	/*
> +	 * for a kdump kernel the reset must be BOOT_ACPI, not BOOT_EFI, as
> +	 * EFI is not enabled in the kdump kernel.
> +	 */
> +	if (is_kdump_kernel())
> +		reboot_type = BOOT_ACPI;

Thanks,

	Ingo

[tip:x86/urgent] x86, UV: Fix kdump reboot

[tip-bot for Cliff Wickman]

Commit-ID:  818987e9a19c52240ba9b1c20f28f047eef76072
Gitweb:     http://git.kernel.org/tip/818987e9a19c52240ba9b1c20f28f047eef76072
Author:     Cliff Wickman <cpw@sgi.com>
AuthorDate: Thu, 31 Mar 2011 09:32:02 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 31 Mar 2011 18:44:03 +0200

x86, UV: Fix kdump reboot

After a crash dump on an SGI Altix UV system the crash kernel
fails to cause a reboot.  EFI mode is disabled in the kdump
kernel, so only the reboot_type of BOOT_ACPI works.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: rja@sgi.com
LKML-Reference: <E1Q5Iuo-00013b-UK@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/apic/x2apic_uv_x.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index d2cf39b..33b10a0 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -24,6 +24,7 @@
 #include <linux/pci.h>
 #include <linux/kdebug.h>
 #include <linux/delay.h>
+#include <linux/crash_dump.h>
 
 #include <asm/uv/uv_mmrs.h>
 #include <asm/uv/uv_hub.h>
@@ -35,6 +36,7 @@
 #include <asm/ipi.h>
 #include <asm/smp.h>
 #include <asm/x86_init.h>
+#include <asm/emergency-restart.h>
 
 DEFINE_PER_CPU(int, x2apic_extra_bits);
 
@@ -811,4 +813,11 @@ void __init uv_system_init(void)
 
 	/* register Legacy VGA I/O redirection handler */
 	pci_register_set_vga_state(uv_set_vga_state);
+
+	/*
+	 * For a kdump kernel the reset must be BOOT_ACPI, not BOOT_EFI, as
+	 * EFI is not enabled in the kdump kernel.
+	 */
+	if (is_kdump_kernel())
+		reboot_type = BOOT_ACPI;
 }

Re: [PATCH v3] x86: UV kdump reboot fix

[Valdis.Kletnieks]

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On Thu, 31 Mar 2011 09:32:02 CDT, Cliff Wickman said:
> From: Cliff Wickman <cpw@sgi.com>
> 
> After a crash dump on an SGI Altix UV system the crash kernel fails to
> cause a reboot.  EFI mode is disabled in the kdump kernel, so only the
> reboot_type of BOOT_ACPI works.

> +	/*
> +	 * for a kdump kernel the reset must be BOOT_ACPI, not BOOT_EFI, as
> +	 * EFI is not enabled in the kdump kernel.
> +	 */
> +	if (is_kdump_kernel())
> +		reboot_type = BOOT_ACPI;
>  }

What happens if some bozo builds their own kdump kernel that has EFI enabled?

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Re: [PATCH v3] x86: UV kdump reboot fix

[Russ Anderson]

On Sat, Apr 02, 2011 at 04:47:37PM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Thu, 31 Mar 2011 09:32:02 CDT, Cliff Wickman said:
> > From: Cliff Wickman <cpw@sgi.com>
> > 
> > After a crash dump on an SGI Altix UV system the crash kernel fails to
> > cause a reboot.  EFI mode is disabled in the kdump kernel, so only the
> > reboot_type of BOOT_ACPI works.
> 
> > +	/*
> > +	 * for a kdump kernel the reset must be BOOT_ACPI, not BOOT_EFI, as
> > +	 * EFI is not enabled in the kdump kernel.
> > +	 */
> > +	if (is_kdump_kernel())
> > +		reboot_type = BOOT_ACPI;
> >  }
> 
> What happens if some bozo builds their own kdump kernel that has EFI enabled?

kdump can use the same EFI enabled kernel currently running on the
system.  When kexec starts the kdump kernel it indicates that
EFI is not enabled so the kernel does not use EFI.  

So what would happen is the bozo built kdump kernel would
work just fine.

There are a lot of detailed discussions of EFI & kdump if you want 
to know the details.
http://lkml.org/lkml/2010/7/27/315

-- 
Russ Anderson, OS RAS/Partitioning Project Lead  
SGI - Silicon Graphics Inc          rja@sgi.com