Re: [PATCH for-7.1 00/11] hw/arm: Add NPCM8XX support

[Peter Maydell <peter.maydell@linaro.org>]

On Thu, 21 Apr 2022 at 17:29, Hao Wu <wuhaotsh@google.com> wrote:
>
> Thanks for all the comments you gave! I'll go over and address them recently.
>
> For this question, The actual CPU should be cortex A35. However, I don't see
> them supported in QEMU. If I inserted CPU with "cortex-a35" QEMU will complain:
> qemu-system-aarch64: missing object type 'cortex-a35-arm-cpu'
>
> What should I do here?

You need to implement the new CPU type first... This means adding
something to target/arm/cpu64.c which will look similar to the
existing CPU handling. You need to watch out for:
 * getting all the ID register values right (check the TRM for the CPU)
 * implementing whatever the right impdef system registers are
 * checking whether QEMU is still missing support for any of the
   architectural features that the A35 implements (what QEMU
   supports is listed in docs/system/arm/emulation.rst)

It's typically not much code but quite a lot of cross-checking
against the TRM for the CPU that we're not missing pieces...
Since you can add the A35 as a supported CPU type for the 'virt'
board you can do A35 support as a separate patchset that doesn't
depend on the npmc8xx work.

https://patchew.org/QEMU/20220417174426.711829-1-richard.henderson@linaro.org/20220417174426.711829-60-richard.henderson@linaro.org/
is an example of how to add a new CPU (in that case the A76), at
the end of a large patchset from RTH that's still going through
code review.

-- PMM