Re: [Qemu-devel] [PATCH 6/8] kvm: consume internal signal with sigtimedwait

[Andreas Färber]

Hello,

Am 22.02.2010 um 22:26 schrieb Marcelo Tosatti:

> Change the way the internal qemu signal, used for communication  
> between
> iothread and vcpus, is handled.
>
> Block and consume it with sigtimedwait on the outer vcpu loop, which
> allows more precise timing control.

Mac OS X v10.5 does not seem to support sigtimedwait():

  CC    arm-softmmu/cpus.o
/Users/andreas/QEMU/qemu/cpus.c: In function ‘qemu_kvm_eat_signals’:
/Users/andreas/QEMU/qemu/cpus.c:379: warning: implicit declaration of  
function ‘sigtimedwait’
/Users/andreas/QEMU/qemu/cpus.c:379: warning: nested extern  
declaration of ‘sigtimedwait’
/Users/andreas/QEMU/qemu/cpus.c:388: warning: implicit declaration of  
function ‘sigbus_reraise’
/Users/andreas/QEMU/qemu/cpus.c:388: warning: nested extern  
declaration of ‘sigbus_reraise’

Could you please add some #ifdef? It used to be an optional POSIX  
extension.

Thanks,
Andreas

> Change from standard signal (SIGUSR1) to real-time one, so multiple
> signals are not collapsed.
>
> Set the signal number on KVM's in-kernel allowed sigmask.
>
> Signed-off-by: Marcelo Tosatti <address@hidden>
> Signed-off-by: Avi Kivity <address@hidden>
> ---
> kvm-all.c |   19 +++++++++++++
> kvm.h     |    1 +
> vl.c      |   89 +++++++++++++++++++++++++++++++++++++++++++++++++++ 
> +--------
> 3 files changed, 97 insertions(+), 12 deletions(-)

> diff --git a/vl.c b/vl.c
> index af198c1..dc05da3 100644
> --- a/vl.c
> +++ b/vl.c

> @@ -3432,11 +3439,36 @@ static void qemu_wait_io_event(CPUState *env)
>     qemu_wait_io_event_common(env);
> }
>
> +static void qemu_kvm_eat_signal(CPUState *env, int timeout)
> +{
> +    struct timespec ts;
> +    int r, e;
> +    siginfo_t siginfo;
> +    sigset_t waitset;
> +
> +    ts.tv_sec = timeout / 1000;
> +    ts.tv_nsec = (timeout % 1000) * 1000000;
> +
> +    sigemptyset(&waitset);
> +    sigaddset(&waitset, SIG_IPI);
> +
> +    qemu_mutex_unlock(&qemu_global_mutex);
> +    r = sigtimedwait(&waitset, &siginfo, &ts);
> +    e = errno;
> +    qemu_mutex_lock(&qemu_global_mutex);
> +
> +    if (r == -1 && !(e == EAGAIN || e == EINTR)) {
> +        fprintf(stderr, "sigtimedwait: %s\n", strerror(e));
> +        exit(1);
> +    }
> +}