[PATCH] x86_64: Fix some comments in tlbflush.h

Were either outdated or misleading.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/include/asm-x86_64/tlbflush.h b/include/asm-x86_64/tlbflush.h
index 061742382520..505b0cf906de 100644
--- a/include/asm-x86_64/tlbflush.h
+++ b/include/asm-x86_64/tlbflush.h
@@ -56,8 +56,9 @@ extern unsigned long pgkern_mask;
  *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
  *  - flush_tlb_pgtables(mm, start, end) flushes a range of page tables
  *
- * ..but the x86_64 has somewhat limited tlb flushing capabilities,
- * and page-granular flushes are available only on i486 and up.
+ * x86-64 can only flush individual pages or full VMs. For a range flush
+ * we always do the full VM. Might be worth trying if for a small
+ * range a few INVLPGs in a row are a win.
  */
 
 #ifndef CONFIG_SMP
@@ -115,7 +116,9 @@ static inline void flush_tlb_range(struct vm_area_struct * vma, unsigned long st
 static inline void flush_tlb_pgtables(struct mm_struct *mm,
                                       unsigned long start, unsigned long end)
 {
-        /* x86_64 does not keep any page table caches in TLB */
+        /* x86_64 does not keep any page table caches in a software TLB.
+           The CPUs do in their hardware TLBs, but they are handled
+           by the normal TLB flushing algorithms. */
 }
 
 #endif /* _X8664_TLBFLUSH_H */