Re: [Qemu-devel] [Bug 1675108] [NEW] Cocoa UI always crashes on startup

[Programmingkid]

On Mar 23, 2017, at 7:35 AM, address@hidden wrote:

> Message: 15
> Date: Thu, 23 Mar 2017 11:13:02 +0000
> From: Alex Benn?e <address@hidden>
> To: Peter Maydell <address@hidden>
> Cc: Bug 1675108 <address@hidden>,     QEMU Developers
>       <address@hidden>, Gerd Hoffmann <address@hidden>
> Subject: Re: [Qemu-devel] [Bug 1675108] [NEW] Cocoa UI always crashes
>       on startup
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=utf-8
> 
> 
> Peter Maydell <address@hidden> writes:
> 
>> On 22 March 2017 at 17:26, Brendan Shanks <address@hidden> wrote:
>>> Public bug reported:
>>> 
>>> Commit 8bb93c6f99a42c2e0943bc904b283cd622d302c5 ("ui/console: ensure
>>> graphic updates don't race with TCG vCPUs") causes the graphic update to
>>> run on a non-main thread, which Cocoa is not happy with. It crashes
>>> immediately after startup.
>> 
>> Oops. Alex, we can't just run UI code on random threads like this.
> 
> Technically its not a random thread its the vCPU context (which ensures
> the vCPU isn't updating while the display is being updated). But I guess
> the Cocoa is limited to not being able to update from an arbitrary
> thread?
> 
> There was a patch posted yesterday to ensure the BQL is held during the
> deferred work but this doesn't look like that.
> 
>> Any ideas?
> 
> Hmm a quick Google seems to imply Cocoa is inflexible in its
> requirements. You can try this ugly but untested patch (I don't have any
> Macs handy):
> 
> modified   ui/console.c
> @@ -1598,8 +1598,16 @@ static void dpy_refresh(DisplayState *s)
>     QLIST_FOREACH(dcl, &s->listeners, next) {
>         if (dcl->ops->dpy_refresh) {
>             if (tcg_enabled()) {
> +#ifdef CONFIG_COCOA
> +                qemu_mutex_unlock_iothread();
> +                start_exclusive();
> +                do_safe_dpy_refresh(first_cpu, RUN_ON_CPU_HOST_PTR(dcl));
> +                end_exclusive();
> +                qemu_mutex_lock_iothread();
> +#else
>                 async_safe_run_on_cpu(first_cpu, do_safe_dpy_refresh,
>                                       RUN_ON_CPU_HOST_PTR(dcl));
> +#endif
>             } else {
>                 dcl->ops->dpy_refresh(dcl);
>             }
> 
> 
> Other than that I guess we need to bring forward the plans to "fixed the 
> dirty tracking
> races in display adapters"
> 
>> 
>> thanks
>> -- PMM
> 
> 
> --
> Alex Benn?e

Your patch does work. I tested it on Mac OS 10.6.8 using qemu-sytem-ppc. 

Has anyone checked on the GTK front-end yet to see if it is having similar 
problems?