From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Fri, 24 Oct 2008 15:45:44 -0400
Subject: [ppc64] kexec/kdump: disable ptcal on QS21
Message-id: 20081024194525.27751.43432.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH 2/2 RHEL5.3 BZ462744] ptcal has to be disabled to use kexec on QS21
Bugzilla: 462744
RH-Acked-by: Neil Horman <nhorman@redhat.com>
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=462744

Description:
===========
We need to disable ptcal before starting a new kernel after a crash,
in order to avoid overwriting data in the kdump kernel.

RHEL Version Found:
================
RHEL 5.2

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1540066

Upstream Status:
================
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.26-rc8/2.6.26-rc8-mm1/broken-out/linux-next.patch

Commit: 5acb08070dcbabf7347ad73cb8a79a145a2a5152 Mon Sep 17 00:00:00 2001

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Test Status:
============
On QS21, when doing a kexec e.g. to save a dump, the ptcal feature has to be
disable, otherwise the system will stop with a "cpu internal fault" and reboot.
Infrastructure to support this has been written by Michael Neuling, posted on
ppc64-dev and accepted upstream. This patch is already included in the 111.el5
RHEL kernel.

With these patches in internal fault is avoided.
===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/arch/powerpc/platforms/cell/ras.c b/arch/powerpc/platforms/cell/ras.c
index 74aa947..2dbaba7 100644
--- a/arch/powerpc/platforms/cell/ras.c
+++ b/arch/powerpc/platforms/cell/ras.c
@@ -8,6 +8,7 @@
 #include <asm/reg.h>
 #include <asm/io.h>
 #include <asm/prom.h>
+#include <asm/kexec.h>
 #include <asm/machdep.h>
 #include <asm/rtas.h>
 #include <asm/cell-regs.h>
@@ -217,6 +218,11 @@ static int cbe_ptcal_notify_reboot(struct notifier_block *nb,
 	return cbe_ptcal_disable();
 }
 
+static void cbe_ptcal_crash_shutdown(void)
+{
+	cbe_ptcal_disable();
+}
+
 static struct notifier_block cbe_ptcal_reboot_notifier = {
 	.notifier_call = cbe_ptcal_notify_reboot
 };
@@ -232,12 +238,20 @@ int __init cbe_ptcal_init(void)
 		return -ENODEV;
 
 	ret = register_reboot_notifier(&cbe_ptcal_reboot_notifier);
-	if (ret) {
-		printk(KERN_ERR "Can't disable PTCAL, so not enabling\n");
-		return ret;
-	}
+	if (ret)
+		goto out1;
+
+	ret = crash_shutdown_register(&cbe_ptcal_crash_shutdown);
+	if (ret)
+		goto out2;
 
 	return cbe_ptcal_enable();
+
+out2:
+	unregister_reboot_notifier(&cbe_ptcal_reboot_notifier);
+out1:
+	printk(KERN_ERR "Can't disable PTCAL, so not enabling\n");
+	return ret;
 }
 
 arch_initcall(cbe_ptcal_init);