Re: [PATCH 0/2] Update use_goto_tb() in hppa and rx targets

[Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>]

пет, 22. мај 2020. у 05:12 Richard Henderson
<richard.henderson@linaro.org> је написао/ла:
>
> On 5/21/20 4:32 AM, Ahmed Karaman wrote:
> > Does this mean that there is a bug
> > in this function for the other targets?
>
> Yes, I think so.
>
> > That we have to do the page crossings check in both modes to avoid the
> > user-mode failures that you have mentioned above?
>
> Well, that or we need to fix linux-user/mmap.c to do all the invalidations
> required.
>

Hi, Mr. Richard, :)

Many thanks for diagnosis, and, more than this, presenting two
alternatives for resolution!

That mmap()... It has been giving us the hardest time since forever,
and it looks it continues to torture us.

It looks we are now between a rock and a hard place. I slightly prefer
the later (fixing mmap.c) alternative, just from the gut feeling that
it is better to fix the problem at its source, rather than to apply
(easy, but possibly performance-wise costly) band-aid to some later
consequence.

But it seem to me that this is as if I say I choose Charybdis, between
Scylla and Charybdis. We also risk jumping out of the frying pan into
the fire.

Adding Laurent, since this is, in essence, a linux-user issue.

If nobody objects, I will instruct Ahmed to file a bug in QEMU Bugzilla.

Wishing to improve the performance, we found the hard bug... eh...

Thanks again to Richard,

Aleksandar

>
> r~
>