[Qemu-devel] qemu crashes with vnc and multiple outputs + console redirection

[Qemu-devel] qemu crashes with vnc and multiple outputs + console redirection

[Christian Borntraeger]

Gerd,

I am playing with the virtio-gpu support on s390 and for that I also wanted to multiplex
the existing consoles. So I basically used the max_outputs=2 of virtio gpu to be able
to switch with ctrl+alt+1 and 3 between the virtio gpu and the sclplm console.

-chardev pty,id=charconsole0 -device sclpconsole,chardev=charconsole0,id=console0
-chardev vc,id=charconsole1 -device sclplmconsole,chardev=charconsole1,id=console1
-device virtio-keyboard-ccw,id=input0,devno=fe.0.0001
-vnc 0.0.0.0:0
-k en-us
-device virtio-gpu-ccw,id=video0,max_outputs=2,devno=fe.0.0008 


This seems to work fine, vrtio-gpu is on 1 and sclplm is on 3. Problem is, 
when I randomly do ctrl+alt+[^1..9] sooner or later qemu crashes with

(gdb) bt
#0  0x000000000123dd9e in surface_width (s=0x0) at /home/cborntra/REPOS/qemu/include/ui/console.h:339
#1  0x000000000123dd9e in vnc_width (vd=vd@entry=0x345e9100) at /home/cborntra/REPOS/qemu/ui/vnc.c:610
#2  0x000000000123df84 in vnc_update_server_surface (vd=vd@entry=0x345e9100) at /home/cborntra/REPOS/qemu/ui/vnc.c:735
#3  0x00000000012437dc in vnc_dpy_switch (dcl=0x345e9140, surface=0x0) at /home/cborntra/REPOS/qemu/ui/vnc.c:756
#4  0x0000000001233456 in console_select (index=index@entry=1) at /home/cborntra/REPOS/qemu/ui/console.c:1039
#5  0x00000000012400ba in do_key_event (vs=vs@entry=0x34652130, down=down@entry=1, keycode=keycode@entry=3, sym=sym@entry=50) at /home/cborntra/REPOS/qemu/ui/vnc.c:1801
#6  0x00000000012406e2 in key_event (vs=vs@entry=0x34652130, down=down@entry=1, sym=<optimized out>) at /home/cborntra/REPOS/qemu/ui/vnc.c:2010
#7  0x0000000001243bea in protocol_client_msg (vs=0x34652130, data=0x346485e0 "\004\001", len=<optimized out>) at /home/cborntra/REPOS/qemu/ui/vnc.c:2341
#8  0x0000000001241bae in vnc_client_read (vs=vs@entry=0x34652130) at /home/cborntra/REPOS/qemu/ui/vnc.c:1511
#9  0x0000000001241c32 in vnc_client_io (ioc=<error reading variable: value has been optimized out>, condition=<error reading variable: value has been optimized out>, opaque=0x34652130, opaque@entry=<error reading variable: value has been optimized out>) at /home/cborntra/REPOS/qemu/ui/vnc.c:1531
#10 0x00000000013015fe in qio_channel_fd_source_dispatch (source=<optimized out>, callback=<optimized out>, user_data=<optimized out>)
    at /home/cborntra/REPOS/qemu/io/channel-watch.c:84
#11 0x000003ff968510aa in g_main_context_dispatch () at /lib64/libglib-2.0.so.0
#12 0x00000000013522e6 in glib_pollfds_poll () at /home/cborntra/REPOS/qemu/util/main-loop.c:214
#13 0x00000000013523ba in os_host_main_loop_wait (timeout=<optimized out>) at /home/cborntra/REPOS/qemu/util/main-loop.c:261
#14 0x0000000001352500 in main_loop_wait (nonblocking=nonblocking@entry=0) at /home/cborntra/REPOS/qemu/util/main-loop.c:515
#15 0x0000000001164a06 in main_loop () at /home/cborntra/REPOS/qemu/vl.c:1940
#16 0x00000000011684d8 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at /home/cborntra/REPOS/qemu/vl.c:4764


any quick idea?

Christian

Re: [Qemu-devel] qemu crashes with vnc and multiple outputs + console redirection

[Gerd Hoffmann]

  Hi,

> I am playing with the virtio-gpu support on s390 and for that I also wanted to multiplex
> the existing consoles.
> So I basically used the max_outputs=2 of virtio gpu to be able
> to switch with ctrl+alt+1 and 3 between the virtio gpu and the sclplm console.

Why max_outputs=2?  Do you want two fbdev devices?

> -chardev pty,id=charconsole0 -device sclpconsole,chardev=charconsole0,id=console0
> -chardev vc,id=charconsole1 -device sclplmconsole,chardev=charconsole1,id=console1
> -device virtio-keyboard-ccw,id=input0,devno=fe.0.0001
> -vnc 0.0.0.0:0
> -k en-us
> -device virtio-gpu-ccw,id=video0,max_outputs=2,devno=fe.0.0008 
> 
> 
> This seems to work fine, vrtio-gpu is on 1 and sclplm is on 3. Problem is, 
> when I randomly do ctrl+alt+[^1..9] sooner or later qemu crashes with

Any chance this is ctrl-alt-2 ?

cheers,
  Gerd

Re: [Qemu-devel] qemu crashes with vnc and multiple outputs + console redirection

[Christian Borntraeger]

On 03/08/2018 04:26 PM, Gerd Hoffmann wrote:
>   Hi,
> 
>> I am playing with the virtio-gpu support on s390 and for that I also wanted to multiplex
>> the existing consoles.
>> So I basically used the max_outputs=2 of virtio gpu to be able
>> to switch with ctrl+alt+1 and 3 between the virtio gpu and the sclplm console.
> 
> Why max_outputs=2?  Do you want two fbdev devices?

I had the situation that the vc device does not appear via vnc
(only the virtio-gpu was then available). But I can no longer reproduce. So
with max_outputs=1 this now works as well. No idea what was wrong. And here
I can no longer see the crash.

> 
>> -chardev pty,id=charconsole0 -device sclpconsole,chardev=charconsole0,id=console0
>> -chardev vc,id=charconsole1 -device sclplmconsole,chardev=charconsole1,id=console1
>> -device virtio-keyboard-ccw,id=input0,devno=fe.0.0001
>> -vnc 0.0.0.0:0
>> -k en-us
>> -device virtio-gpu-ccw,id=video0,max_outputs=2,devno=fe.0.0008 
>>
>>
>> This seems to work fine, vrtio-gpu is on 1 and sclplm is on 3. Problem is, 
>> when I randomly do ctrl+alt+[^1..9] sooner or later qemu crashes with
> 
> Any chance this is ctrl-alt-2 ?

yes.