kvm > 61 segfaults when started with a bridged tap

kvm > 61 segfaults when started with a bridged tap

[iMil]

Hi,

Since I upgraded my ubuntu machine to 8.04, 
/usr/local/bin/qemu-system-x86_64 segfaults when starting with -net 
tap,ifname=tap0 flags. Of course, it's been recompiled.

$ sudo /usr/local/bin/qemu-system-x86_64 /data/virt/netbsd.img -net 
nic,macaddr=00:56:01:02:03:04 -net tap,ifname=tap0,script=/etc/qemu-ifup
Segmentation fault

I see the same behaviour with any NIC, and for kvm from -62 to -67 (I 
tested each version). 
Downgrading to kvm-61 fixes the problem. It seems like there's a similar 
bug report here: 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=476469

The VM also start correctly with qemu.

$ modinfo kvm-intel
filename:       /lib/modules/2.6.24-16-generic/extra/kvm-intel.ko
license:        GPL
author:         Qumranet
version:        kvm-67
srcversion:     2E2C88C6F09E216FDAA6797
depends:        kvm
vermagic:       2.6.24-16-generic SMP mod_unload 586
parm:           bypass_guest_pf:bool
parm:           enable_vpid:bool
parm:           flexpriority_enabled:bool

$ uname -a
Linux tatooine 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC 2008 i686 
GNU/Linux

$ cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 15
model name	: Intel(R) Core(TM)2 CPU          6300  @ 1.86GHz
stepping	: 6
cpu MHz		: 1596.000
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 2
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 10
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm 
constant_tsc arch_perfmon pebs bts pni monitor ds_cpl vmx est tm2 ssse3 
cx16 xtpr lahf_lm
bogomips	: 3736.56
clflush size	: 64

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model		: 15
model name	: Intel(R) Core(TM)2 CPU          6300  @ 1.86GHz
stepping	: 6
cpu MHz		: 1596.000
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 1
cpu cores	: 2
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 10
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm 
constant_tsc arch_perfmon pebs bts pni monitor ds_cpl vmx est tm2 ssse3 
cx16 xtpr lahf_lm
bogomips	: 3733.37
clflush size	: 64

Interesting packages

ii  bridge-utils                                 1.2-2
ii  iproute                                      20071016-2ubuntu1
ii  libc6                                        2.7-10ubuntu3

Hope this helps,

regards

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Emile "iMil" Heitor <imil@home.imil.net>                                  _
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Re: kvm > 61 segfaults when started with a bridged tap

[Avi Kivity]

iMil wrote:
> Hi,
>
> Since I upgraded my ubuntu machine to 8.04, 
> /usr/local/bin/qemu-system-x86_64 segfaults when starting with -net 
> tap,ifname=tap0 flags. Of course, it's been recompiled.
>
> $ sudo /usr/local/bin/qemu-system-x86_64 /data/virt/netbsd.img -net 
> nic,macaddr=00:56:01:02:03:04 -net tap,ifname=tap0,script=/etc/qemu-ifup
> Segmentation fault
>   

Please generate a core and post a stacktrace.  You'll probably need to 
set 'ulimit -c unlimited' in order to get a core.

-- 
error compiling committee.c: too many arguments to function


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

[iMil]

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

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Emile "iMil" Heitor <imil@home.imil.net>                                  _
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