Re: kvm enable over cortex-a53?

[Marc Zyngier <marc.zyngier@arm.com>]

On Wed, Jun 04 2014 at  7:19:42 am BST, Lei Wen <adrian.wenl@gmail.com> wrote:
> On Tue, Jun 3, 2014 at 5:11 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
>> On Tue, Jun 03 2014 at  3:14:33 am BST, Lei Wen <adrian.wenl@gmail.com> wrote:
>>> Hi Marc,
>>>
>>> On Mon, Jun 2, 2014 at 5:27 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
>>>> kvmtool tells you where the console lives (it is one of the virtio-mmio
>>>> devices that it prints out when it starts). The address you quote
>>>> (assuming that this is an IPA) doesn't seem to have anything to do with
>>>> anything kvmtool emulates. Pretty sure your kernel is trying to poke at
>>>> some area without parsing the device tree...
>>>
>>> Do you have any suggestion for how to debug it?...
>>
>> I suggest you start with a very simple guest kernel config (only virtio
>> drivers), no additional stuff. My gut feeling is that you have stuff in
>> your 3.10 kernel that shouldn't be there.
>>
>> Your best bet would probably to use a recent tree for your guests.
>
> I see.
> After remove the earlyprintk=uart8250-32bit,0xd4030000 in the kvmtool
> command line, the KVM_EXIT_MMIO message is gone.

Not surprising. Telling the kernel to poke random addresses that are
only relevant to the host is never going to have the effect you seem to
expect.

> But the console is silence afterward, supposing there is something
> wrong in boot the guest kernel.
> Is there some method to access the guest kernel's log buffer?
> Or some other way to output the guest kernel's message with earlyprintk?

If using kvmtool, the method is to use "earlyprintk=uart8250-32bit,0x3f8".

> I see virtio_block is defined in foundation-v8.dts, is it a must to have
> such device node? Shall I map the uart phys register range by
> this node?

No. The host devices are not delevant to the guest at all. The guest
never accesses any physical devices apart from GIC and timers. kvmtool
creates a completely virtual platform that has nothing to do with the
host.

You don't have to touch kvmtool at all, this is a self-contained
platform emulation. If it doesn't work properly, there is only two
options:
- your guest is not configured properly
- the KVM backport to your 3.10 kernel is less than perfect.

Overall, you'd be much better off using a mainline kernel with a model,
get familiar with the tools and configurations, and only then try to
replicate this on your HW.

	M.
-- 
Jazz is not dead. It just smells funny.