[Qemu-devel] Re: GSOC 2011

[yajin]

> On Wed, Feb 16, 2011 at 07:32:31PM -0500, yajin wrote:
>> Hi all,
>
> Hi,
>
>> I have proposed an idea of GSOC 2011 about adding KVM support to MIPS
>> architecture. I have solid experience on MIPS architecture and
>> familiar with qemu. I am very interested in this project.
>
> Having KVM support for MIPS would be really great. AFAIK there is not
> hardware virtualization support on MIPS (except if you plan to use the
> supervisor mode for that), so how do you plan to proceed here? Executing
> everything in user mode and emulating the trapped instructions? MIPS is
> using a split address space depending on the mode, so that may not be
> that easy.

Hi Aurelien, thanks for your reply. You are right. MIPS does NOT have
hardware virtualization support currently. And I do not want to use
the supervisor thing because this mode has been deprecated. Supervisor
mode is now optional according to MIPS32 documents. So for the
privilege instructions, the trap-emulation is the easy way although
the performance may be not good. We may improve the performance after
make this work.

MIPS has an unique feature(or problem for virtualization) is that the
MMU is bypassed by kseg0(and kseg1), in which the kernel code is
residing. There are two possible solutions to this problem. The first
one is we can trap all the access of kseg0 to VMM. The second one is
to remap the guest kernel to other segment. This first one is
transparent to guest kernel. However it will cause tremendous
performance lost since the access of kseg0 is very common. The second
one needs to make a little changes to the link script of guest linux
kernel.

>
> All of that to say it would be nice to have a more detailed description
> about such a GSOC, describing the your exact plans with a rough
> timeline. This is especially true, given that adding support for a new
> architecture in KVM seems to be a huge task for a GSOC.
>
> The best is probably to fill a new entry on the wiki, at this address:
>
>  http://wiki.qemu.org/Google_Summer_of_Code_2011

I will make an entry on the wiki and keep it update.

>
>> According to the GSOC, there should be a mentor to each participating
>> project. Is there anyone interested to be the mentor of this project?
>> I would be honored to work with you.
>
> I know almost nothing about KVM, so if we go for a GSOC about adding KVM
> support to MIPS, it would be nice to have another mentor who have a good
> knowledge about KVM. I am pretty fine with the MIPS part though.
>

Thanks very much. Hope we can work together and make it happen.

-----

yajin