Re: [PATCH 2/3] target/arm: Refactor default generic timer frequency handling

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

On 4/19/24 11:46, Peter Maydell wrote:
> The generic timer frequency is settable by board code via a QOM
> property "cntfrq", but otherwise defaults to 62.5MHz.  The way this
> is done includes some complication resulting from how this was
> originally a fixed value with no QOM property.  Clean it up:
> 
>   * always set cpu->gt_cntfrq_hz to some sensible value, whether
>     the CPU has the generic timer or not, and whether it's system
>     or user-only emulation
>   * this means we can always use gt_cntfrq_hz, and never need
>     the old GTIMER_SCALE define
>   * set the default value in exactly one place, in the realize fn
> 
> The aim here is to pave the way for handling the ARMv8.6 requirement
> that the generic timer frequency is always 1GHz.  We're going to do
> that by having old CPU types keep their legacy-in-QEMU behaviour and
> having the default for any new CPU types be a 1GHz rather han 62.5MHz
> cntfrq, so we want the point where the default is decided to be in
> one place, and in code, not in a DEFINE_PROP_UINT64() initializer.
> 
> This commit should have no behavioural changes.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/arm/internals.h |  7 ++++---
>   target/arm/cpu.c       | 31 +++++++++++++++++--------------
>   target/arm/helper.c    | 16 ++++++++--------
>   3 files changed, 29 insertions(+), 25 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~