Re: [PATCH] [PATCH] system/memory: Fix max access size

[Philippe Mathieu-Daudé]

On 22/7/24 13:53, Paolo Bonzini wrote:
> On Sat, Jul 20, 2024 at 4:30 PM Peter Maydell <peter.maydell@linaro.org> wrote:
> > If the HPET timer device is supposed to permit 64 bit writes and it is not
> > doing so, then that needs to be fixed in the HPET timer device model, by
> > making sure that its read/write functions correctly handle the size=8 case
> > and then setting access_size_max =8 in its MemoryRegionOps struct.
>
> It does, and I've started looking into it[1].
>
> The replacement for this patch is simple (on top of that branch):
>
> diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
> index 5e60fedc089..ac55dd1ebd6 100644
> --- a/hw/timer/hpet.c
> +++ b/hw/timer/hpet.c
> @@ -637,6 +637,10 @@ static const MemoryRegionOps hpet_ram_ops = {
>           .min_access_size = 4,
>           .max_access_size = 8,
>       },
> +    .impl = {
> +        .min_access_size = 4,
> +        .max_access_size = 8,

It seems this model could be simplified using .min_access_size = 8,
letting the core memory layer handle the % 4 byte accesses (the
read path is obvious, the write one a bit less). Nothing urgent,
possibly a BitSizedTask.

> +    },
>       .endianness = DEVICE_NATIVE_ENDIAN,
>   };
>
> I'll now look into the other patch for interrupts. Thanks for testing
> my changes!
>
> Paolo
>
> [1] https://gitlab.com/bonzini/qemu/-/commits/hpet