Re: [PATCH v2 2/3] arm/mpu: Provide and populate MPU C data structures

[Julien Grall <julien@xxxxxxx>]

Hi Ayan,

On 09/06/2025 09:27, Ayan Kumar Halder wrote:
> On 09/06/2025 08:41, Orzel, Michal wrote:
> > > diff --git a/xen/arch/arm/include/asm/mpu/regions.inc b/xen/arch/arm/ 
> > > include/asm/mpu/regions.inc
> > > index 6b8c233e6c..631b0b2b86 100644
> > > --- a/xen/arch/arm/include/asm/mpu/regions.inc
> > > +++ b/xen/arch/arm/include/asm/mpu/regions.inc
> > > @@ -24,7 +24,7 @@
> > >   #define XEN_MPUMAP_ENTRY_SHIFT  0x3     /* 8 byte structure */
> > >   .macro store_pair reg1, reg2, dst
> > > -    .word 0xe7f000f0                    /* unimplemented */
> > > +    stm \dst, {\reg1, \reg2}  /* reg2 should be a higher register 
> > > than reg1 */
> > Didn't we agree not to use STM (I suggested it but then Julien pointed 
> > out that
> > it's use in macro might not be the best)?
> Ah my last response was not sent.
>
> I realized that I cannot use strd due to the following error
>
> Error: first transfer register must be even -- `strd r3,r4,[r1]'
Ah I missed the "even" part when reading the specification. However, we 
control the set of registers, so we can't we follow the restriction? 
This would be better...
> So,  I am using stm with the following comment
... than a comment and hoping the developper/reviewer will notice it 
(the code is also misplaced). I am ready to bet this will likely cause 
some problem in the future.
Cheers,

--
Julien Grall