Re: [PATCH] system/physmem: Fix cpu_memory_rw_debug for armv7m MPU

[xndcn <xndchn@gmail.com>]

Got it, thanks.
It seems like there is still a lot of work surrounding the API, so I
create a issue to track it
https://gitlab.com/qemu-project/qemu/-/issues/2697

On Mon, Nov 25, 2024 at 5:23 AM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 11/23/24 22:30, xndcn wrote:
> > Thanks. This patch at least guarantees normal read/write access to
> > addresses with r/w flags, although there is still a risk of
> > misidentifying accessible regions within continuous address spaces.
> >
> > Actually, initially I did write a patch with a modified page size as
> > an argument, but I soon found that the current implementation of
> > armv7a (pmsav7) will return the page size (lg_page_size) as 0 in many
> > situations (such as overlapping regions).
>
> 0 was arbitrarily chosen as "anything less than TARGET_PAGE_BITS".
>
> > Maybe we can simply make the page size as 2^5 (minimal page size) when
> > the returned lg_page_size == 0?
>
> No, don't lie, or make unhelpful guesses at the generic level. The only thing you could do
> for arm m-profile is give accurate information, which for now will be immediately
> discarded as *still* being less than TARGET_PAGE_BITS.  But I do have plans for that.
>
> Anyway, nothing you do with page sizes is helpful along the debug path.  For that, we need
> to swap away from "pages" to "ranges", where some ranges are in fact pages, but others
> aren't.  This means changing the API for cpu_get_phys_<something>_debug.
>
>
> r~