[Qemu-devel] [Bug 595438] Re: KVM segmentation fault, using SCSI+writeback and linux 2.4 guest

[Jes Sorensen]

Could you try and run this in GDB and get the backtrace when it crashes?
Just do:

gdb /usr/bin/kvm
(gdb) set args -M pc-0.12 -enable-kvm -m 256 -smp 1 -name spamsender -uuid 
b9cacd5e-08f7-41fd-78c8-89cec59af881 -chardev 
socket,id=monitor,path=/var/lib/libvirt/qemu/spamsender.monitor,server,nowait 
-monitor chardev:monitor -boot d -drive 
file=/mnt/megadiff/cdiso_400_130.iso,if=ide,media=cdrom,index=2 -drive 
file=/home/mmarkk/spamsender2.img,if=scsi,index=0,format=qcow2,cache=writeback 
-net nic,macaddr=00:00:00:00:00:00,vlan=0,name=nic.0 -net tap,vlan=0,name=tap.0 
-chardev pty,id=serial0 -serial chardev:serial0 -parallel none -usb -vnc 
127.0.0.1:0 -vga cirrus
(gdb) run
<after crash>
(gdb) bt

Make sure to have all the debug packages installed, otherwise the
backtrace isn't really useful.

Unfortunately the core file you posted isn't of use to anyone who
doesn't have Ubuntu installed with the exact packages you have
installed. It just shows some random addresses in gdb.

Thanks,
Jes

-- 
KVM segmentation fault, using SCSI+writeback and linux 2.4 guest
https://bugs.launchpad.net/bugs/595438
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Status in QEMU: New

Bug description:
I Use Ubuntu 32 bit 10.04 with standard KVM.
I have Intel E7600  @ 3.06GHz processor with VMX

In this system I Run:
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin 
QEMU_AUDIO_DRV=none /usr/bin/kvm -M pc-0.12 -enable-kvm -m 256 -smp 1 -name 
spamsender -uuid b9cacd5e-08f7-41fd-78c8-89cec59af881 -chardev 
socket,id=monitor,path=/var/lib/libvirt/qemu/spamsender.monitor,server,nowait 
-monitor chardev:monitor -boot d -drive 
file=/mnt/megadiff/cdiso_400_130.iso,if=ide,media=cdrom,index=2 -drive 
file=/home/mmarkk/spamsender2.img,if=scsi,index=0,format=qcow2,cache=writeback 
-net nic,macaddr=00:00:00:00:00:00,vlan=0,name=nic.0 -net tap,vlan=0,name=tap.0 
-chardev pty,id=serial0 -serial chardev:serial0 -parallel none -usb -vnc 
127.0.0.1:0 -vga cirrus

.iso image contain custom distro of 2.4-linux kernel based system. During 
install process (when .tar.gz actively unpacked), kvm dead with segmentation 
fault.

And ONLY when I choose scsi virtual disk and writeback simultaneously. 
But, writeback+ide, writethrough+scsi works OK.

I use qcow2. It seems, that qcow does not have such problems.

Virtual machine get down at random time during file copy. It seems, when qcow2 
file size need to be expanded.