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

Hello Oleksandr,

On 20/05/16 15:19, Oleksandr Dmytryshyn wrote:
On Fri, May 20, 2016 at 12:59 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
On 20.05.16 at 10:45, <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx> wrote:
On Thu, May 19, 2016 at 5:36 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
On 19.05.16 at 15:58, <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx> 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.


[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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