lkml.org 
[lkml]   [2011]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMIC instead of jmp5 +0
From
Date
On Fri, 2011-10-14 at 14:53 -0700, H. Peter Anvin wrote:
> On 10/13/2011 11:37 AM, Steven Rostedt wrote:
> > On Thu, 2011-10-13 at 09:57 -0700, Jeremy Fitzhardinge wrote:
> >> On 10/13/2011 08:40 AM, H. Peter Anvin wrote:
> >>> On 10/12/2011 05:08 PM, Jeremy Fitzhardinge wrote:
> >>>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> >>>>
> >>>> GENERIC_NOP5_ATOMIC should make a better nop.
> >>>>
> >>> On 32 bits, yes. On 64 bits you should use P6_NOP5_ATOMIC.
> >>
> >> Something like this?
> >>
> >
> > No, we only care about 5byte nops here. Look at ideal_nop in
> > alterative.c
> >
>
> He needs a compile-time alternative.

I didn't explain this well. I actually just meant something like:

#ifdef CONFIG_X86_64
# define IDEAL_NOP5 P6_NOP5_ATOMIC
#else
# define IDEAL_NOP5 GENERIC_NOP5_ATOMIC
#endif

That is, we know we are using this for a 5byte jump. Just keep it simple
for that. Do you envision needing other nops too? Well, we could do 2
byte nops, but I think we could use the same for both. Can't we?

-- Steve




\
 
 \ /
  Last update: 2011-10-15 02:25    [W:0.052 / U:0.008 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site