Re: Qemu mipssim patches, mips malta and virtio bugs

[Philippe Mathieu-Daudé]

On 2/13/21 11:05 AM, Reinoud Zandijk wrote:
> On Fri, Feb 12, 2021 at 10:44:55AM +0100, Philippe Mathieu-Daudé wrote:
>>>> i'd like to get the following simple patches to the MIPS/mipssim target 
>>>> adding
>>>> virtio-mmio devices to it.
>>
>> Please submit your patches as a series so we can review them on
>> the list:
>> https://wiki.qemu.org/Contribute/SubmitAPatch#Use_git_format-patch
> 
> Oh thanks, i didn't know that; i've created a new patch with the OR gate you
> suggested. We deliberated about the change here and we'll at least keep it
> here locally for testing and profiling code until a real `virt' platform is
> developed for MIPS. Until then it would IMHO be a good expansion to mipssim.
> I'll try to get a proper patch posted on the list :)

What I forgot to mention is that QEMU aims to keep models the closer
to the hardware, so modifying MIPSsim to some Frankenstein is unlikely
to be accepted.

The patch could be useful (we can adapt it to an eventual 'virt'
machine later).

> As for the Malta target, its missing its BIOS and thus its PCI bus is not
> initialised correctly for NetBSD to run on when its passed with -kernel. Linux
> seems to bodge around this somewhere but if no BIOS is found it would be
> better if it was initialised as the BIOS would leave it before handing over to
> the kernel.

Agreed. The current "pseudo bootloader" was developed with Linux guest
in mind. For anything else you need a real BIOS ROM, but even there I'm
not sure it works well, because the GT64120 north bridge is reset in a
particular state suitable for Linux.

> There are also a few Qemu virtio-pci and virtio-mmio bugs we encountered on
> Aarch64 and Sparc64, how can I best file those? Or should I try to contact ppl
> directly?

For now the bug tracking system is on Launchpad:
https://bugs.launchpad.net/qemu/+filebug

You can contact the maintainers directly, but if the bug is complex and
will take time to fix, it is better to track it with a LP ticket IMO.

Regards,

Phil.