Subject: Re: [RFC Patch 6/6] Adapt kexec and samples code to recognise PPC64 hardware breakpoint usage

From: Michael Ellerman <[email-masked]>
Date: Fri, 15 May 2009 00:11:57 +1000

On Thu, 2009-05-14 at 15:59 +0200, Geert Uytterhoeven wrote:
> On Thu, 14 May 2009, K.Prasad wrote:
> > Modify kexec code to disable DABR registers before a reboot. Adapt the samples
> > code to populate PPC64-arch specific fields.
> > 
> > Signed-off-by: K.Prasad <[email-masked]>
> > ---
> >  arch/powerpc/kernel/machine_kexec_64.c   |    6 
> >  samples/hw_breakpoint/data_breakpoint.c  |    4 
> > 
> > Index: linux-2.6-tip.hbkpt/arch/powerpc/kernel/machine_kexec_64.c
> > ===================================================================
> > --- linux-2.6-tip.hbkpt.orig/arch/powerpc/kernel/machine_kexec_64.c	2009-05-14 00:17:24.000000000 +0530
> > +++ linux-2.6-tip.hbkpt/arch/powerpc/kernel/machine_kexec_64.c	2009-05-14 09:48:09.000000000 +0530
> > @@ -24,6 +24,7 @@
> >  #include <asm/sections.h>	/* _end */
> >  #include <asm/prom.h>
> >  #include <asm/smp.h>
> > +#include <asm/hw_breakpoint.h>
> >  
> >  int default_machine_kexec_prepare(struct kimage *image)
> >  {
> > @@ -214,6 +215,9 @@
> >  	put_cpu();
> >  
> >  	local_irq_disable();
> > +#ifdef CONFIG_PPC64
>    ^^^^^^^^^^^^^^^^^^^
> > +	hw_breakpoint_disable();
> > +#endif
>    ^^^^^^
> 
> What about providing a dummy definition of hw_breakpoint_disable()
> in <asm/hw_breakpoint.h> if !CONFIG_PPC64?

That would be good.

What would be better, is to notice that machine_kexec_64.c is only ever
built for 64-bit - hence the name. And so no ifdefs or anything else is
required.

cheers