Re: [PATCH RFC 13/18] xen: introduce and use 'dom0_rambase_pfn' setting for kernel Dom0

[Julien Grall <julien.grall@arm.com>]

Hello Oleksandr,

On 20/05/16 15:19, Oleksandr Dmytryshyn wrote:
> On Fri, May 20, 2016 at 12:59 PM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 20.05.16 at 10:45, <oleksandr.dmytryshyn@globallogic.com> wrote:
>>> On Thu, May 19, 2016 at 5:36 PM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>>>> On 19.05.16 at 15:58, <oleksandr.dmytryshyn@globallogic.com> wrote:
>>>>> Case 1: Dom0 is driver domain:
>>>>> There is a Ducati firmware which runs on dedicated M4 core and decodes
>>>>> video. This firmware uses hardcoded physical addresses for graphics
>>>>> buffers. Those addresses should be inside address-space of the driver
>>>>> domain (Dom0). Ducati firmware is proprietary and we have no ability
>>>>> to rework it. So Dom0 kernel should be placed to the configured
>>>>> address (to the DOM0 RAM bank with specific address).
>>>>>
>>>>> Case 2: Dom0 is Thin and DomD is driver domain.
>>>>> All is the same: Ducati firmware requires special (hardcoded) addresses.
>>>>
>>>> For both of these cases I would then wonder whether such
>>>> environments are actually suitable for doing virtualization on.
>>> Currently we use Jacinto 6 evaluation board with DRA74X processor.
>>> We have both configurations (Thin Dom0 and Thich Dom0).
>>
>> Which says nothing about their suitability for virtualization.
> Our solution is based on Jacinto 6 evaluation board with DRA74X
> processor. We need video-playback. Ducati firmware decodes video and
> it works only with hardcoded addresses so we need this patch.

This patch is a way to solve the problem and may not be the only one.
I would like to explore all the possibilities before taking an approach 
that requires to modify the memory allocator in Xen.

In my previous mails, I suggested a different solution (see [1] and 
[2]). If you think it is not suitable, please share more details or 
explain why you think your patch is the only way to solve it.

Regards,

[1] 
http://lists.xenproject.org/archives/html/xen-devel/2016-05/msg01879.html
[2] 
http://lists.xenproject.org/archives/html/xen-devel/2016-05/msg01894.html

-- 
Julien Grall

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