Re: [PATCH v1 2/3] arm/mpu: Provide and populate MPU C data structures

[Julien Grall <julien@xxxxxxx>]

On 05/06/2025 09:58, Julien Grall wrote:
> Hi Michal,
>
> On 05/06/2025 08:44, Orzel, Michal wrote:
> > On 04/06/2025 19:43, Ayan Kumar Halder wrote:
> > > Do the arm32 equivalent initialization for commit id ca5df936c4.
> > This is not a good commit msg.
> > Also, we somewhat require passing 12 char long IDs.
> We are following the same convention as Linux. IIRC this was updated 
> because there was some collision with 10 characters in Linux (not sure 
> if we have seen it in Xen yet).
> [...]
>
> > > diff --git a/xen/arch/arm/include/asm/mpu/regions.inc b/xen/arch/arm/ 
> > > include/asm/mpu/regions.inc
> > > index 6b8c233e6c..943bcda346 100644
> > > --- a/xen/arch/arm/include/asm/mpu/regions.inc
> > > +++ b/xen/arch/arm/include/asm/mpu/regions.inc
> > > @@ -24,7 +24,13 @@
> > >   #define XEN_MPUMAP_ENTRY_SHIFT  0x3     /* 8 byte structure */
> > >   .macro store_pair reg1, reg2, dst
> > > -    .word 0xe7f000f0                    /* unimplemented */
> > > +    str \reg1, [\dst]
> > > +    add \dst, \dst, #4
> > > +    str \reg2, [\dst]
> > AFAIR there is STM instruction to do the same
> AFAICT, one issue with stm is the ordering is forced by the instruction 
> rather than the user. So \reg1 could be stored first.
Sorry I meant \reg2.

Cheers,

--
Julien Grall