[OpenBIOS] [PATCH 0/2] Sparc64: virtio-block and interrupt support

[Artyom Tarasenko]

On Sat, May 12, 2012 at 5:15 PM, Mark Cave-Ayland
<mark.cave-ayland at ilande.co.uk> wrote:
> On 12/05/12 15:14, Artyom Tarasenko wrote:
>
>> On Sat, May 12, 2012 at 3:54 PM, Blue Swirl<blauwirbel at gmail.com>  wrote:
>>>
>>> On Sat, May 12, 2012 at 1:34 PM, Artyom Tarasenko<atar4qemu at gmail.com>
>>>  wrote:
>>>>
>>>> On Sat, May 12, 2012 at 1:42 PM, Blue Swirl<blauwirbel at gmail.com>
>>>>  wrote:
>>>>>
>>>>> Based on Artyom's Sparc64 work (thanks a lot!), I added some minimal
>>>>> support for virtio-block and interrupt nodes.
>>>>
>>>>
>>>> Hey, that was fast! Does it mean your patches also allow booting from
>>>> a virtio device?
>>>
>>>
>>> No, only a warning for the unknown device is avoided and Linux can use
>>> the interrupts.
>>>
>>> Making a simple driver does not look very difficult, here are some
>>> examples:
>>> http://fxr.watson.org/fxr/source/dev/virtio/block/virtio_blk.c
>>> http://fxr.watson.org/fxr/source/drivers/block/virtio_blk.c?v=linux-2.6
>>>
>>> http://git.qemu.org/?p=seabios.git;a=blob;f=src/virtio-blk.c;h=194deaf98b41a3b10fa6b7e0f49e9fa091a83222;hb=HEAD
>>>
>>
>> Fair enough. On the other hand, if we implement it too soon, there
>> will be less motivation in fixing the cmd646 emulation in qemu... ;-)
>
>
> What's the actual bug with cmd646 in QEMU?

It doesn't work. :)
There seems to be quite  a few cmd646 modifications. Some were capable
of DMA, which Linux tries to use.
The qemu implementation doesn't provide dma: IOMMU/DVMA are not implemented.
But why it doesn't work in PIO mode - I don't know.

-- 
Regards,
Artyom Tarasenko

solaris/sparc under qemu blog: http://tyom.blogspot.com/search/label/qemu