Re: [RFC PATCH 16/40] target/arm: Represent the entire MPIDR_EL1

[Richard Henderson <richard.henderson@linaro.org>]

On 1/6/23 11:16, Peter Maydell wrote:
> On Tue, 3 Jan 2023 at 18:24, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> Replace ARMCPU.mp_affinity with CPUARMState.cp15.mpidr_el1,
>> setting the additional bits as required.  In particular,
>> always set the U bit when there is only one cpu in the system.
>> Remove the mp_is_up bit which attempted to do the same thing.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   target/arm/cpu.h     |  7 ++--
>>   target/arm/cpu.c     | 80 +++++++++++++++++++++++++++++++++++++-------
>>   target/arm/cpu_tcg.c |  1 -
>>   target/arm/helper.c  | 25 ++------------
>>   target/arm/hvf/hvf.c |  2 +-
>>   target/arm/kvm64.c   |  4 +--
>>   6 files changed, 75 insertions(+), 44 deletions(-)
> 
> Based purely on the diffstat it's not super-obvious why this
> is an improvement. What's the rationale ?

It gets rid of cpu->mp_is_up, set only by cortex-r5, and then generalizes.

> Side note, we don't currently handle the MT bit, where some
> CPUs end up putting the cpu number in the Aff1 field rather
> than Aff0. We ideally ought to handle that too.

Would that be set by the board as well?  I don't think we model cpu 
packages/clusters/whatchacallums at that level currently.


r~