linux-kernel - [PATCH] [33/40] i386: Allow boot-time disable of paravirt

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Date:	Mon, 30 Apr 2007 12:28:08 +0200 (CEST)
From:	Andi Kleen <ak@...e.de>
To:	jeremy@...p.org, rusty@...tcorp.com.au, ak@...e.de,
	patches@...-64.org, linux-kernel@...r.kernel.org
Subject: [PATCH] [33/40] i386: Allow boot-time disable of paravirt_ops patching


From: Jeremy Fitzhardinge <jeremy@...p.org>

Add "noreplace-paravirt" to disable paravirt_ops patching.

Signed-off-by: Jeremy Fitzhardinge <jeremy@...source.com>
Signed-off-by: Andi Kleen <ak@...e.de>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Andi Kleen <ak@...e.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 Documentation/kernel-parameters.txt |    3 +++
 arch/i386/kernel/alternative.c      |   13 +++++++++++++
 2 files changed, 16 insertions(+)

Index: linux/Documentation/kernel-parameters.txt
===================================================================
--- linux.orig/Documentation/kernel-parameters.txt
+++ linux/Documentation/kernel-parameters.txt
@@ -64,6 +64,7 @@ parameter is applicable:
 	GENERIC_TIME The generic timeofday code is enabled.
 	NFS	Appropriate NFS support is enabled.
 	OSS	OSS sound support is enabled.
+	PV_OPS	A paravirtualized kernel
 	PARIDE	The ParIDE subsystem is enabled.
 	PARISC	The PA-RISC architecture is enabled.
 	PCI	PCI bus support is enabled.
@@ -1142,6 +1143,8 @@ and is between 256 and 4096 characters. 
 
 	nomce		[IA-32] Machine Check Exception
 
+	noreplace-paravirt	[IA-32,PV_OPS] Don't patch paravirt_ops
+
 	noreplace-smp	[IA-32,SMP] Don't replace SMP instructions
 			with UP alternatives
 
Index: linux/arch/i386/kernel/alternative.c
===================================================================
--- linux.orig/arch/i386/kernel/alternative.c
+++ linux/arch/i386/kernel/alternative.c
@@ -30,6 +30,16 @@ static int __init setup_noreplace_smp(ch
 }
 __setup("noreplace-smp", setup_noreplace_smp);
 
+#ifdef CONFIG_PARAVIRT
+static int noreplace_paravirt = 0;
+
+static int __init setup_noreplace_paravirt(char *str)
+{
+	noreplace_paravirt = 1;
+	return 1;
+}
+__setup("noreplace-paravirt", setup_noreplace_paravirt);
+#endif
 
 #define DPRINTK(fmt, args...) if (debug_alternative) \
 	printk(KERN_DEBUG fmt, args)
@@ -330,6 +340,9 @@ void apply_paravirt(struct paravirt_patc
 {
 	struct paravirt_patch_site *p;
 
+	if (noreplace_paravirt)
+		return;
+
 	for (p = start; p < end; p++) {
 		unsigned int used;
 
-
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