Re: [Qemu-devel] [Question]Support of China loogson processor

[Leon Alrae <leon.alrae@imgtec.com>]

On 15/04/2015 10:35, James Hogan wrote:
> On 13/04/15 12:29, vt wrote:
>> Hi, guys
>>  
>> I saw the architecture code about mips in the qemu and kvm modules, so it is no doubt that mips cpu can be supported.
>> But I wonder if anyone have used qemu/kvm virtualization with China loongson processor (MIPS architecture) without modification of qemu/kvm code.
>> All the infomation I have searched in the Internet can't answer my question. 
>>  
>> If anyone have done that before, let me know it will not  be a dead end.
>>  
>> Thanks
>> Sangfor VT
> 
> I haven't attempted it on Loongson yet, but it'd be interesting to see
> whether it works. You'd still have to emulate a Malta guest at the
> moment. Getting it to work on the Ingenic XBurst cores required a little
> effort in the kernel due to slight incompatibilities with the MIPS32r2
> spec, so its possible there'll be problems with Loongson too.
> 
> I presume Loongson may use highmem, if so you'll want to disable it. I
> still need to get those patches sorted out.
> 
> Let us know how it goes or if you hit problems!

Since I also haven't had a chance to test Loongson emulation, I thought
I'd give it a try (TCG only, Loongson-2E cpu and fulong2e machine).

Good news is that I'm able to get to the login prompt using ancient QEMU
v1.0, kernel 2.6.33 (with additional patch from
https://lists.gnu.org/archive/html/qemu-devel/2010-06/msg02566.html) and
some old debian image I had handy. However, in any newer version
starting from v1.1.0 of QEMU something goes horribly wrong and it just
segfaults somewhere inside hw/bonito.c quite early during kernel
booting. I haven't looked deeper, but it seems it's not in the best shape...

Leon