[Xen-devel] Re: [patch 14/26] Xen-paravirt_ops: add common patching machinery

[Rusty Russell <rusty@xxxxxxxxxxxxxxx>]

On Fri, 2007-03-16 at 10:20 +0100, Ingo Molnar wrote:
> * Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> 
> > Implement the actual patching machinery.  paravirt_patch_default() 
> > contains the logic to automatically patch a callsite based on a few 
> > simple rules:
> > 
> >  - if the paravirt_op function is paravirt_nop, then patch nops
> >  - if the paravirt_op function is a jmp target, then jmp to it
> >  - if the paravirt_op function is callable and doesn't clobber too much
> >     for the callsite, call it directly
> > 
> > paravirt_patch_default is suitable as a default implementation of 
> > paravirt_ops.patch, will remove most of the expensive indirect calls 
> > in favour of either a direct call or a pile of nops.
> 
> Acked-by: Ingo Molnar <mingo@xxxxxxx>

I like this one too, but note that it needs a twist when we change to
use direct calls to wrappers for the Great paravirt_ops Unexporting.

Rusty.



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