Re: [PATCH-for-8.2] target/arm/cpu: Allow logging disabled CPU features at UNIMP level

[Alex Bennée]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> Some CPU features aren't strictly required to run guest code (such
> debugging features), so we don't model them. To prevent the guest
> to access non-existent system registers, we disable the feature bit
> in the ID registers (see commit 7d8c283e10 "target/arm: Suppress more
> TCG unimplemented features in ID registers").
>
> Since it might be useful to know when a CPU supposed to implement a
> feature has it disabled in QEMU, provide the ability to log disabled
> features at the UNIMP level:
>
>   $ qemu-system-aarch64 -M virt -d unimp -S -cpu neoverse-v1
>   QEMU 8.0.92 monitor - type 'help' for more information
>   CPU#0: Disabling unimplemented feature 'FEAT_SPE (Statistical Profiling 
> Extension)' for neoverse-v1
>   CPU#0: Disabling unimplemented feature 'FEAT_TRF (Self-hosted Trace 
> Extension)' for neoverse-v1
>   CPU#0: Disabling unimplemented feature 'FEAT_TRF (Self-hosted Trace 
> Extension)' for neoverse-v1
>   CPU#0: Disabling unimplemented feature 'Trace Macrocell system register 
> access' for neoverse-v1
>   CPU#0: Disabling unimplemented feature 'Trace Macrocell system register 
> access' for neoverse-v1
>   CPU#0: Disabling unimplemented feature 'Memory-mapped Trace' for
>   neoverse-v1

Don't these also depend on FEAT_?

Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro