Re: [PATCH 0/7] semihosting: proper QEMU exit on semihosted exit syscall

[Peter Maydell <peter.maydell@linaro.org>]

On Mon, 20 Jun 2022 at 15:25, Luc Michel <lmichel@kalray.eu> wrote:
> This series implements a clean way for semihosted exit syscalls to
> terminate QEMU with a given return code.
>
> Until now, exit syscalls implementations consisted in calling exit()
> with the wanted return code. The problem with this approach is that
> other CPUs are not properly stopped, leading to possible crashes in
> MTTCG mode, especially when at_exit callbacks have been registered. This
> can be the case e.g., when plugins are in use. Plugins can register
> at_exit callbacks. Those will be called on the CPU thread the exit
> syscall is comming from, while other CPUs can continue to run and thus
> call other plugin callbacks.

The other option would be to say "if you register an atexit
callback in your plugin that's your problem to sort out" :-)
There's lots of situations where code inside QEMU might just
call exit(), not just this one. (Mostly these are "we detected
an error and decided to just bail out" codepaths.)

Is there a situation where we get a crash that doesn't involve
code in a plugin doing something odd?

thanks
-- PMM