Re: [Qemu-devel] Problems with qemu "modern" virtio on sparc64

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Jan 06, 2017 at 11:48:37PM +0200, Michael S. Tsirkin wrote:
> On Fri, Jan 06, 2017 at 01:05:46PM -0800, Guenter Roeck wrote:
> > On Fri, Jan 06, 2017 at 07:42:19PM +0000, Mark Cave-Ayland wrote:
> > > On 06/01/17 18:34, Guenter Roeck wrote:
> > > 
> > > > On Fri, Jan 06, 2017 at 05:04:58PM +0000, Mark Cave-Ayland wrote:
> > > >> On 30/12/16 19:57, Guenter Roeck wrote:
> > > >>
> > > >> Disabling "modern" mode enables boot to proceed as normal:
> > > >>
> > > >> $ ./qemu-system-sparc64 \
> > > >> -drive
> > > >> file=debian-9.0-sparc64-NETINST1.iso,if=none,index=0,id=cd,media=cdrom \
> > > >> -device virtio-blk-pci,disable-modern=on,drive=cd \
> > > >> -nographic \
> > > >> -bios openbios-builtin.elf.nostrip \
> > > >> -m 256
> > > >>
> > > > ...
> > > >>
> > > >> Guenter, can you try a similar command line and confirm whether it fixes
> > > >> the issue for you under QEMU 2.7 and 2.8? I have no idea as to why the
> > > >> difference in legacy/non-legacy codepaths should crash the kernel though.
> > > >>
> > > > Unfortunately, my qemu command line wizard capabilities are somewhat lacking.
> > > > I had tried that before, but just could not figure out how to change my command
> > > > line to include "disable-modern=on". If you have an idea, please let me know.
> > > > Here it is:
> > > > 
> > > > ${QEMU} -M ${mach} -cpu "${cpu}" -m 512 \
> > > > 	        -drive file=${rootfs},if=virtio \
> > > > 		-net nic,model=virtio \
> > > > 		-kernel arch/sparc/boot/image -no-reboot \
> > > > 		-append "root=/dev/vda init=/sbin/init.sh console=ttyS0" \
> > > > 		-nographic 
> > > 
> > > If you apply the same principles from my example above to your command
> > > line then you should end up with something like:
> > > 
> > > ${QEMU} -M ${mach} -cpu "${cpu}" -m 512 \
> > >         -drive file=${rootfs},if=none,id=hd \
> > > 	-device virtio-blk-pci,disable-modern=on,drive=hd \
> > > 	-net nic,model=virtio \
> > > 	-kernel arch/sparc/boot/image -no-reboot \
> > > 	-append "root=/dev/vda init=/sbin/init.sh console=ttyS0" \
> > > 	-nographic
> > > 
> > That works, but only if I drop "-net nic,model=virtio". Otherwise I get
> > the same crash again. Any idea how to set the network configuration
> > the same way ?
> > 
> > Thanks,
> > Guenter
> 
> Replace it with -device virtio-net-pci.
> 

Excellent, that works. Setting either entry to "disable-modern=off" crashes
as observed earlier.

Thanks,
Guenter