Re: Thoughts on removing the TARGET_I386 part of hw/display/vga/vbe_portio_list[]

[Mark Cave-Ayland]

On 06/12/2022 16:23, Richard Henderson wrote:

> On 12/6/22 10:02, Peter Maydell wrote:
> > On Tue, 6 Dec 2022 at 15:56, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> > > On 6/12/22 13:30, Dr. David Alan Gilbert wrote:
> > > > I don't know that bit of qemu well enough to know whether the cpu part
> > > > of qemu should be splitting the unaligned accesses or not.
> > > All I/O accesses are gated thru access_with_adjusted_size() in
> > > softmmu/memory.c.
> > >
> > > There is an old access_with_adjusted_size_unaligned() version [1] from
> > > Andrew and a more recent series [2] from Richard. Maybe the latter fixes
> > > some long-standing bug [3] we have here?
> >
> > There definitely are some unaddressed bugs there -- maybe this
> > is the time to work through what semantics we want that
> > softmmu code to provide and fix the bugs...
>
> Yes, indeed.  Let's not forget Mark C-A's m68k bug[1] which so far has no 
> resolution.
>
> r~
>
> [1] https://gitlab.com/qemu-project/qemu/-/issues/360

That would definitely be useful: since Richard worked on this series, I managed to 
develop a hack that allows me to work around the issue for my particular use-case 
which is why I haven't been focusing on this.

The main concerns are listed in the above issue at 
https://gitlab.com/qemu-project/qemu/-/issues/360#note_597130838. Defining the 
behaviour doesn't seem too bad, but it is likely some things that unintentionally 
depend upon the existing behaviour will break.


ATB,

Mark.