linux-kernel - Re: [Patch 01/12] Prepare the code for Hardware Breakpoint interfaces

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Date:	Wed, 27 May 2009 14:19:17 +0530
From:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>
Subject: Re: [Patch 01/12] Prepare the code for Hardware Breakpoint
	interfaces

On Wed, May 27, 2009 at 03:01:15AM +0200, Frederic Weisbecker wrote:
> On Thu, May 21, 2009 at 07:30:33PM +0530, K.Prasad wrote:
> > This patch introduces header files containing constants, structure definitions
> > and declaration of functions used by the hardware breakpoint interface code.
> > 
> > Original-patch-by: Alan Stern <stern@...land.harvard.edu>
> > Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com>
> > Reviewed-by: Alan Stern <stern@...land.harvard.edu>
> > ---
> > Index: linux-2.6-tip.hbkpt/arch/x86/include/asm/processor.h
> > ===================================================================
> > --- linux-2.6-tip.hbkpt.orig/arch/x86/include/asm/processor.h
> > +++ linux-2.6-tip.hbkpt/arch/x86/include/asm/processor.h
> > @@ -29,6 +29,7 @@ struct mm_struct;
> >  #include <linux/threads.h>
> >  #include <linux/init.h>
> >  
> > +#define HBP_NUM 4
> >  /*
> >   * Default implementation of macro that returns current
> >   * instruction pointer ("program counter").
> > @@ -433,12 +434,11 @@ struct thread_struct {
> >  #endif
> >  	unsigned long		gs;
> >  	/* Hardware debugging registers: */
> > -	unsigned long		debugreg0;
> > -	unsigned long		debugreg1;
> > -	unsigned long		debugreg2;
> > -	unsigned long		debugreg3;
> > +	unsigned long		debugreg[HBP_NUM];
> 
> 
> 
> Note that each patches must leave a buildable kernel, even
> if these patches are contained in a set logic.
> 
> I haven't tried yet, but I suspect this patch, if applied
> without the rest, will cause a build error.
> 
> There are still some sites that use the removed fields above.
> 
> A solution would be to temporarily fix these sites in this patch
> by using the new debugreg array interface. Even if you remove
> some of them in further patches in this series, for example
> by using the new load_debug_registers() helper, it will follow
> the logic step by step and leave a buildable kernel at each
> middle step.
> 
> That implies to modify also some of the other patches of this
> series, but all of these changes should be trivial.
> 
> Thanks,
> 
> Frederic.
>

The debugreg<n> removal patches were correct, even as recent as
http://lkml.org/lkml/2009/5/11/160 and I guess I messed-up meanwhile.
Thanks for pointing it out - I've now moved them to Patch 8/12 along
with the ptrace changes.

The rest of the patches allow the kernel tree to be compiled though.
Would you prefer a new iteration with these changes, or can I send
individual patches with the changes discussed above?

Thanks,
K.Prasad
 
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