Re: [Qemu-devel] [PATCH 0/6] accel/tcg: Support execution from MMIO and small MMU regions

[Peter Maydell]

On 16 July 2018 at 13:30, KONRAD Frederic <address@hidden> wrote:
> Hi Peter,
>
> Nice! Thanks for that.
>
> A little question though.. What will happen in the case where the
> CPU start executing code at random place because of eg: a badly
> configured kernel?
>
> Seeing the patch 5 I guess it will really execute stuff.. So
> maybe this is less user-friendly?

Yes, it's true that we will now happily execute from anything
(device, unassigned memory, etc), and do what the real hardware
would do in that situation (random unhelpful things, infinite
loop of taking exceptions). That's a bit unavoidable though I
think, and there are already lots of cases where QEMU will just
sit there with a black screen because the user has loaded in
a bad guest image that goes off into the weeds without printing
anything to a UART.

It's possible we could devise a user-friendliness option that
tried to pick up symptoms of guests being stuck (eg tracking
whether we're continuously taking exceptions) but that gets
into heuristics a bit.

thanks
-- PMM