Re: [PATCH v1] xen/arm: arm32: Add support to identify the Cortex-R52 processor

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

On 20/06/2023 17:41, Julien Grall wrote:
> Hi,
Hi Julien,
> On 20/06/2023 16:17, Ayan Kumar Halder wrote:
> > Add a special configuration (CONFIG_AARCH32_V8R) to setup the Cortex-R52
> > specifics.
> >
> > Cortex-R52 is an Arm-V8R AArch32 processor.
> >
> > Refer ARM DDI 0487I.a ID081822, G8-9647, G8.2.112 MIDR,
> > bits[31:24] = 0x41 , Arm Ltd
> > bits[23:20] = Implementation defined
> > bits[19:16] = 0xf , Arch features are individually identified
> > bits[15:4] = Implementation defined
> > bits[3:0] = Implementation defined
> >
> > Thus, the processor id is 0x410f0000 and the processor id mask is
> > 0xff0f0000
> >
> > Also, there is no special initialization required for R52.
> Are you saying that Xen upstream + this patch will boot on Cortex-R52?
This patch will help for earlyboot of Xen. With this patch, cpu_init() 
will work on Cortex-R52.
There will be changes required for the MPU configuration, but that will 
be sent after Penny's patch serie "[PATCH v2 00/41] xen/arm: Add 
Armv8-R64 MPU support to Xen - Part#1" is upstreamed.
My aim is to extract the non-dependent changes and send them for review.

> > Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
> > ---
> >   xen/arch/arm/Kconfig         |  7 +++++++
> >   xen/arch/arm/arm32/Makefile  |  1 +
> >   xen/arch/arm/arm32/proc-v8.S | 32 ++++++++++++++++++++++++++++++++
> >   3 files changed, 40 insertions(+)
> >   create mode 100644 xen/arch/arm/arm32/proc-v8.S
> >
> > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> > index 61e581b8c2..c45753a2dd 100644
> > --- a/xen/arch/arm/Kconfig
> > +++ b/xen/arch/arm/Kconfig
> > @@ -3,6 +3,13 @@ config ARM_32
> >       depends on "$(ARCH)" = "arm32"
> >       select ARCH_MAP_DOMAIN_PAGE
> >   +config AARCH32_V8R
> > +    bool "AArch32 Arm V8R Support (UNSUPPORTED)" if UNSUPPORTED
> > +    def_bool n
> > +    depends on ARM_32
> > +    help
> > +      This option enables Armv8-R profile for AArch32.
> > +
> >   config ARM_64
> >       def_bool y
> >       depends on !ARM_32
> > diff --git a/xen/arch/arm/arm32/Makefile b/xen/arch/arm/arm32/Makefile
> > index 520fb42054..2ab808a7a8 100644
> > --- a/xen/arch/arm/arm32/Makefile
> > +++ b/xen/arch/arm/arm32/Makefile
> > @@ -8,6 +8,7 @@ obj-y += head.o
> >   obj-y += insn.o
> >   obj-$(CONFIG_LIVEPATCH) += livepatch.o
> >   obj-y += proc-v7.o proc-caxx.o
> > +obj-$(CONFIG_AARCH32_V8R) += proc-v8.o
> >   obj-y += smpboot.o
> >   obj-y += traps.o
> >   obj-y += vfp.o
> > diff --git a/xen/arch/arm/arm32/proc-v8.S b/xen/arch/arm/arm32/proc-v8.S
> > new file mode 100644
> > index 0000000000..c5a566b165
> > --- /dev/null
> > +++ b/xen/arch/arm/arm32/proc-v8.S
> Below you say the file will contain v8r specific initialization. So 
> please rename it to proc-v8r.S.
Ack.

- Ayan

> Cheers,