On 08/17/2011 07:32 PM, Yong Zhang wrote:

On Wed, Aug 17, 2011 at 10:17:52AM -0700, David Daney wrote:

quoted

quoted

diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index 46c4763..f48b18e 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S

@@ -441,7 +441,7 @@ sys_call_table:
  	PTR	sys_fremovexattr		/* 4235 */
  	PTR	sys_tkill
  	PTR	sys_sendfile64
-	PTR	compat_sys_futex
+	PTR	sys_32_futex

This change is redundant, scall64-o32.S already does the right thing

My first virsion(not sent out) doesn't include scall64-o32.S either.

quoted

so additional zero extending is not needed and is just extra
instructions to execute for no reason.

Why I'm adding it here is for:
1)code consistent, otherwise we must move SYSCALL_DEFINE6(32_futex,...)
   under CONFIG_MIPS32_N32;

No, you don't have to move it.  Just don't call it.

2)I'm afraid there may be some other way to touch the high 32-bit of a
   register, so touching scall64-o32.S is also for safety(due to unknown
   reason, fix me if I'm wrong).

OK: You are mistaken.  You claim you don't understand what the code 
does.  That is really a poor justification for modifying it.

David Daney