Re: [PATCH] xen/arm32: head: Update the documentation for register r12

[Julien Grall <julien@xxxxxxx>]

On 28/02/2022 13:04, Michal Orzel wrote:
> Hi Julien,
Hi Michal,

Thank you for the review.

> On 28.02.2022 11:11, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > Since commit 54c4ae18d158 ("xen/arm32: head: Rework and document
> > launch()"), the boot code is not using the register r12.
> >
> > So update the documentation to show r12 has no specific purpose.
> >
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/arm32/head.S | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
> > index 13cfc837d39c..78274a1c034f 100644
> > --- a/xen/arch/arm/arm32/head.S
> > +++ b/xen/arch/arm/arm32/head.S
> > @@ -79,7 +79,7 @@
> >    *   r9  - paddr(start)
> >    *   r10 - phys offset
> >    *   r11 - UART address
> > - *   r12 - is_secondary_cpu
> > + *   r12 -
> >    *   r13 - SP
> >    *   r14 - LR
> >    *   r15 - PC
> FWICS, there are still 2 instructions in this file assigning #0 or #1 to r12 
> and each of them
> has a comment "/* r12 := is_secondary_cpu */". >
> So I have 2 questions:
> 1. Do we even need these instructions? (I do not think so)
We don't need them. I will drop them and respin the patch.

Cheers,

--
Julien Grall