Re: kvm > 61 segfaults when started with a bridged tap

[iMil <imil@home.imil.net>]

Hi list,

some month ago, I submitted this issue: 
http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg16688.html

Recently, I "solved" the problem, here's how :

The backtrace of the generated core dump showed the following :

Program terminated with signal 11, Segmentation fault.
[New process 11204]
#0  0xb7d36e66 in ?? () from /lib/tls/i686/cmov/libc.so.6
(gdb) bt
#0  0xb7d36e66 in ?? () from /lib/tls/i686/cmov/libc.so.6
#1  0xb7d38edd in ?? () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7d3a9ff in calloc () from /lib/tls/i686/cmov/libc.so.6
#3  0xb7715131 in xcb_connect_to_fd () from /usr/lib/libxcb.so.1
#4  0xb7717a51 in xcb_connect () from /usr/lib/libxcb.so.1
#5  0xb784b717 in _XConnectXCB () from /usr/lib/libX11.so.6
#6  0xb7834029 in XOpenDisplay () from /usr/lib/libX11.so.6
#7  0xb7e8986e in ?? () from /usr/lib/libSDL-1.2.so.0
#8  0xb7e94dec in ?? () from /usr/lib/libSDL-1.2.so.0
#9  0xb7e7fbf6 in SDL_VideoInit () from /usr/lib/libSDL-1.2.so.0
#10 0xb7e535c3 in SDL_InitSubSystem () from /usr/lib/libSDL-1.2.so.0
#11 0xb7e53627 in SDL_Init () from /usr/lib/libSDL-1.2.so.0
#12 0x080c2d46 in sdl_display_init (ds=0xb7eb8354, full_screen=0, 
no_frame=0)
     at sdl.c:635
#13 0x0805985e in main (argc=11, argv=0xbfc88474)
     at /home/imil/src/kvm-75/qemu/vl.c:10011

considering that the SDL initialization lead to a crash, I started 
QEMU/KVM with the -nographic flag... and it worked. At this point, I 
noticed that :

. Starting QEMU/KVM with the -net nic option (without specifying a model) 
+ default SDL output : Segfault
. Starting QEMU/KVM without -net nic + default SDL output :  everything's 
fine except, obviously, the network
. Starting QEMU/KVM with the net -nic option along with -nographic : 
everything's fine except I don't have SDL output (didn't tried VNC)

Then I tried to specifiy a NIC model (model=i82557b) and everything just 
worked, this is my fix.

As far as I can tell, the following configuration is buggy (for me at 
least) :

. Ubuntu Hardy (8.04), 2.6.24-19-generic
. QEMU/KVM > 61 (till I figured out how to solve this issue, I used KVM > 
61 with QEMU/KVM 61)
. Default rtl8139 NIC
. SDL output

Googling showed me only one person that seems to have the same issue under 
Debian (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=476469), but on 
another machine of mine running Debian Lenny, I never had this problem.

Hope this helps,

regards

----------------------------------------
Emile "iMil" Heitor <imil@home.imil.net>                                  _
                    http://gcu-squad.org            ASCII ribbon campaign ( )
                                                     - against HTML email  X
                                                                 & vCards / \