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

[Richard Henderson]

On 6/20/22 07:24, Luc Michel wrote:
> Hi,
>
> 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 semihosting_exit_request function provides a mean to cleanly
> terminate QEMU. It introduces an new exit reason
> (SHUTDOWN_CAUSE_GUEST_SEMI_EXIT) used in this case. The CPU is stopped
> and returns to the main CPU loop so that no more instruction get
> executed (the semihosting_exit_request is declared G_NORETURN).
>
> All targets are converted to use this new function.

Did you test a complete build?  At a glance I would guess that arm-linux-user will no 
longer link because qemu_set/get_exit_status is missing.


r~

> Thanks,
> Luc
>
> Luc Michel (7):
>    softmmu: add qemu_[set|get]_exit_status functions
>    semihosting: add the semihosting_exit_request function
>    semihosting/arm-compat-semi: use semihosting_exit_request
>    target/m68k: use semihosting_exit_request on semihosted exit syscall
>    target/mips: use semihosting_exit_request on semihosted exit syscall
>    target/nios2: use semihosting_exit_request on semihosted exit syscall
>    target/xtensa: use semihosting_exit_request on semihosted exit syscall
>
>   qapi/run-state.json                |  4 +++-
>   include/semihosting/semihost.h     |  4 ++++
>   include/sysemu/sysemu.h            |  2 ++
>   semihosting/arm-compat-semi.c      |  3 +--
>   semihosting/config.c               | 17 +++++++++++++++++
>   softmmu/main.c                     |  2 +-
>   softmmu/runstate.c                 | 11 +++++++++++
>   target/m68k/m68k-semi.c            |  4 ++--
>   target/mips/tcg/sysemu/mips-semi.c |  2 +-
>   target/nios2/nios2-semi.c          |  4 ++--
>   target/xtensa/xtensa-semi.c        |  2 +-
>   11 files changed, 45 insertions(+), 10 deletions(-)