Re: hang after seabios

["Richard W.M. Jones" <rjones@redhat.com>]

On Wed, Jul 30, 2014 at 03:58:43PM -0700, Zetan Drableg wrote:
>    [00183ms] /usr/libexec/qemu-kvm \
>        -global virtio-blk-pci.scsi=off \
>        -nodefconfig \
>        -nodefaults \
>        -nographic \
>        -machine accel=kvm:tcg \
>        -cpu host,+kvmclock \
>        -m 500 \
>        -no-reboot \
>        -kernel /var/tmp/.guestfs-0/kernel.47903 \
>        -initrd /var/tmp/.guestfs-0/initrd.47903 \
>        -device virtio-scsi-pci,id=scsi \
>        -drive file=/tmp/libguestfs-test-tool-sda-Iakpwe,cache=none,format
>    =raw,id=hd0,if=none \
>        -device scsi-hd,drive=hd0 \
>        -drive file=/var/tmp/.guestfs-0/root.47903,snapshot=on,id=appliance,
>    if=none,cache=unsafe \
>        -device scsi-hd,drive=appliance \
>        -device virtio-serial \
>        -serial stdio \
>        -device sga \
>        -chardev socket,path=/tmp/libguestfspx9994/guestfsd.sock,id=channel0
>    \
>        -device virtserialport,chardev=channel0,name=org.libguestfs.channel.0
>    \
>        -append 'panic=1 console=ttyS0 udevtimeout=600 no_timer_check
>    acpi=off printk.time=1 cgroup_disable=memory root=/dev/sdb selinux=0
>    guestfs_verbose=1 TERM=xterm edd=off'
>    \x1b[1;256r\x1b[256;256H\x1b[6n
>    Google, Inc.
>    Serial Graphics Adapter 10/14/11
>    SGABIOS $Id: sgabios.S 8 2010-04-22 00:03:40Z nlaredo $ (mockbuild@
>    ca-build44.us.oracle.com) Fri Oct 14 20:04:36 UTC 2011
>    Term: 80x24
>    4 0
>    SeaBIOS (version seabios-0.6.1.2-28.el6)
>    \x1b[2J
> 
> At this point it hangs forever.

These hangs can be tricky to diagnose.

There are a couple of things you can do however:

(1) strace qemu to find out what it is doing, or:

(2) [harder, but much more informative] gdb into the guest to find out
where the guest hangs, or:

(3) Take the command line above, and cut it down to try to isolate the
problematic options.  I would concentrate on the following options as
being most likely to cause trouble:

 -cpu
 -machine
 -kernel
 -device sga (remove it)

For (1) and (2) you can use a qemu wrapper to modify the qemu command
that the test tool runs.

See also:

http://libguestfs.org/guestfs.3.html#qemu-wrappers

http://rwmj.wordpress.com/2011/10/12/tip-debugging-the-early-boot-process-with-qemu-and-gdb/#content

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html