Re: [patches] [PATCH] [4/12] x86_64: Disable CLFLUSH supportagain

From: Jan Beulich
Date: Thu Aug 09 2007 - 08:53:24 EST


The 64-bit conditional seems wrong to me, I'd assume you mean

if (1 || !cpu_has_clflush)

Jan

>>> Andi Kleen <ak@xxxxxxx> 09.08.07 14:41 >>>

It turns out CLFLUSH support is still not complete; we
flush the wrong pages. Again disable it for the release.
Noticed by Jan Beulich.

Signed-off-by: Andi Kleen <ak@xxxxxxx>

---
arch/i386/mm/pageattr.c | 2 +-
arch/x86_64/mm/pageattr.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)

Index: linux/arch/i386/mm/pageattr.c
===================================================================
--- linux.orig/arch/i386/mm/pageattr.c
+++ linux/arch/i386/mm/pageattr.c
@@ -82,7 +82,7 @@ static void flush_kernel_map(void *arg)
struct page *p;

/* High level code is not ready for clflush yet */
- if (cpu_has_clflush) {
+ if (0 && cpu_has_clflush) {
list_for_each_entry (p, lh, lru)
cache_flush_page(p);
} else if (boot_cpu_data.x86_model >= 4)
Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86_64/mm/pageattr.c
+++ linux/arch/x86_64/mm/pageattr.c
@@ -75,7 +75,8 @@ static void flush_kernel_map(void *arg)

/* When clflush is available always use it because it is
much cheaper than WBINVD. */
- if (!cpu_has_clflush)
+ /* clflush is still broken. Disable for now. */
+ if (0 && !cpu_has_clflush)
asm volatile("wbinvd" ::: "memory");
else list_for_each_entry(pg, l, lru) {
void *adr = page_address(pg);
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