x86: add noclflush option
To disable CLFLUSH usage, especially in change_page_attr().
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b8fadf5..040e30a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1191,6 +1191,8 @@
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
+ noclflush [BUGS=X86] Don't use the CLFLUSH instruction
+
nohlt [BUGS=ARM]
no-hlt [BUGS=X86-32] Tells the kernel that the hlt
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index dfc9563..56b7ea8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -542,6 +542,13 @@
}
#endif
+static __init int setup_noclflush(char *arg)
+{
+ setup_clear_cpu_cap(X86_FEATURE_CLFLSH);
+ return 1;
+}
+__setup("noclflush", setup_noclflush);
+
void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)
{
char *vendor = NULL;
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index df15952..cb9b8a9 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -1032,6 +1032,13 @@
}
+static __init int setup_noclflush(char *arg)
+{
+ setup_clear_cpu_cap(X86_FEATURE_CLFLSH);
+ return 1;
+}
+__setup("noclflush", setup_noclflush);
+
void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)
{
if (c->x86_model_id[0])
