Re: [Qemu-devel] Running KVM guest on X86

[Gleb Natapov]

On Thu, Aug 09, 2012 at 05:39:36PM +0000, Bhushan Bharat-R65777 wrote:
> 
> 
> > -----Original Message-----
> > From: Stuart Yoder [mailto:address@hidden
> > Sent: Thursday, August 09, 2012 8:28 PM
> > To: Bhushan Bharat-R65777
> > Cc: Alex Williamson; address@hidden; Avi Kivity
> > Subject: Re: [Qemu-devel] Running KVM guest on X86
> > 
> > On Tue, Aug 7, 2012 at 1:30 AM, Bhushan Bharat-R65777 <address@hidden>
> > wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: Alex Williamson [mailto:address@hidden
> > >> Sent: Monday, August 06, 2012 9:27 PM
> > >> To: Bhushan Bharat-R65777
> > >> Cc: address@hidden; Avi Kivity
> > >> Subject: Re: Running KVM guest on X86
> > >>
> > >> On Mon, 2012-08-06 at 15:40 +0000, Bhushan Bharat-R65777 wrote:
> > >> > Hi Avi/All,
> > >> >
> > >> > I am facing issue to boot KVM guest on x86 (I used to work on
> > >> > PowerPC platform
> > >> and do not have enough knowledge of x86). I am working on making VFIO
> > >> working on PowerPC Booke, So I have cloned Alex Williamsons git
> > >> repository, compiled kernel for x86 on fedora with virtualization
> > >> configuration (selected all kernel config options for same). Run
> > >> below command to boot Guest (I have not provided vfio device yet):
> > >> >
> > >> > "qemu-system-x86_64 -enable-kvm -m 1024 -nographic -kernel
> > >> arch/x86_64/boot/bzImage -initrd /boot/initramfs-3.5.0-rc4+.img
> > >> -serial tcp::4444,server,telnet"
> > >> >
> > >> > After the I can see qemu command line (able to run various commands
> > >> > like "info
> > >> registers" etc), while guest does not boot (not even the first print 
> > >> comes).
> > >> >
> > >> > Can anyone help in what I am missing or doing wrong?
> > >>
> > >> x86 doesn't use the serial port for console by default, so you're
> > >> making things quite a bit more difficult that way.  Typically you'll
> > >> want to provide a disk image (the -hda option is the easiest way to
> > >> do this), a display (-vga std -vnc :0 is again easiest), and probably
> > >> something to install from (-cdrom <image.iso>).  You can also add a
> > >> -boot d to get it to choose the cdrom the first time for install.
> > >> Thanks,
> > >
> > > Thanks Avi and Alex, I can see the KVM guest boot prints by adding -append
> > "console=ttyS0"
> > 
> > Note, once you get to user space you will need a getty specified in
> > inittab in order to get a login on your serial port.   Something like:
> > 
> >    T0:23:respawn:/sbin/getty -L ttyS0
> 
> 1)
> I tried booting with prebuilt qcow2 then it works for me:
> qemu-system-x86_64  -enable-kvm  -nographic  -device sga  -m 1024 -hda 
> debian_squeeze_amd64_standard.qcow2
> 
> Does anyone help on how I can add my kernel to qcow2? Or create a proper 
> qcow2?
> 
> 2)
> Also I tried as mentioned in section "3.9 Direct Linux Boot": 
> http://qemu.weilnetz.de/qemu-doc.html#disk_005fimages : 
> 
> qemu-kvm  -enable-kvm  -nographic -kernel /boot/vmlinuz-3.5.0+ -hda 
> /boot/initramfs-3.5.0+.img  -append "console=ttyS0 root=/dev/sda" -m 1024 
> 
-hda  /boot/initramfs-3.5.0+.img is incorrect. Should be -hda
debian_squeeze_amd64_standard.qcow2 -initrd /boot/initramfs-3.5.0+.img
and root=/dev/sda1 probably.

> I get below error :
> [    1.299225] No filesystem could mount root, tried:  ext3 ext2 ext4 iso9660
> [    1.303232] Kernel panic - not syncing: VFS: Unable to mount root fs on 
> unknown-block(8,0)
> [    1.307683] Pid: 1, comm: swapper/0 Not tainted 3.3.5-2.fc16.x86_64 #1
> [    1.311201] Call Trace:
> [    1.312548]  [<ffffffff815eac62>] panic+0xba/0x1cd
> [    1.315160]  [<ffffffff81cf1075>] mount_block_root+0x258/0x283
> [    1.318275]  [<ffffffff81cf10f3>] mount_root+0x53/0x57
> [    1.321047]  [<ffffffff81cf1234>] prepare_namespace+0x13d/0x176
> [    1.324206]  [<ffffffff81cf0d59>] kernel_init+0x156/0x15b
> [    1.327114]  [<ffffffff81089587>] ? schedule_tail+0x27/0xb0
> [    1.330102]  [<ffffffff815fd6a4>] kernel_thread_helper+0x4/0x10
> [    1.333413]  [<ffffffff81cf0c03>] ? start_kernel+0x3c5/0x3c5
> [    1.336446]  [<ffffffff815fd6a0>] ? gs_change+0x13/0x13
> 
> Thanks
> -Bharat
> 

--
                        Gleb.