On 07/14/2011 08:23 AM, Avi Kivity wrote:
On 07/14/2011 04:17 PM, Pekka Enberg wrote:
>
> I still don't follow. The guest oopses? dmesg | less. An issue with
> tools/kvm? gdb -p `pgrep kvm`.
When I was debugging tools/kvm virtio code, I used to 'instrument' the
guest kernel with printk() calls which helped a lot.
Sure, but do you really need it spewing out the serial port all the time?
Also, a bug in tools/kvm can manifest in many interesting ways in the
guest kernel during boot, for example. You can't do dmesg then and gdb
won't save you. I think you've lived too long in the table KVM and Qemu
land to remember how important reliable printk() is for development.
I guess. Also I've switched to trace_printk() since it's much nicer (and
intergrates with other ftrace features).
And again, I'm not against tools/kvm optimizing serial. I just want
better justification for socket-mmio.
Just to be really thorough, the optimization is incorrect for UART
emulation. Maybe for a simple PIO based console where there were no
guest visible side effects to a character write, this would be okay, but
that is not how a UART works.
Just implement virtio-serial :-) You can move data as fast as you'd
like through it.
And if virtio-serial is too complicated, make a simpler version that
doesn't have such crazy semantics.
Regards,
Anthony Liguori
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