Re: [Xen-devel] [PATCH V4] xen/arm: domain_build: allocate lowmem for dom0 as much as possible

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

Julien,

>> What we estimate now is a thin Dom0 without any drivers running with
>> ramdisk. All drivers would be moved to a special guest domain.
>
> You may want to give a look what has been done on x86 with the "Dedicated
> hardware domain".
I have to look at the stuff.

> Another solution, is rather than moving the devices in a separate domain,
> you move the toolstack.
I see the point.
But there are number of different reasons to have a thin initial
domain. F.e. system boot time optimization which is critical for
applications we focus on.
For cases as following: a thin initial domain would start special
domain, i.e. responsible for CAN communication (with minimal needed
devices set) prior one with rich devices set, and a domain actually
running IVI (with PV drivers only) would be started finally.

> The latter may cause less trouble on platform without SMMU.
I hope we do switch to a IOMMU capable platform. But still have some
flashbacks to IOMMU-less systems.

Sincerely,
Andrii Anisov.


On Mon, Nov 14, 2016 at 10:30 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi Andrii,
>
> On 14/11/2016 03:11, Andrii Anisov wrote:
>>>
>>> There are many reasons: for example because you want Dom0 to be Linux
>>> and the storage driver domain to be FreeBSD. Or because you want the
>>> network driver domain to be QNX.
>>
>> What we estimate now is a thin Dom0 without any drivers running with
>> ramdisk. All drivers would be moved to a special guest domain.
>
>
> You may want to give a look what has been done on x86 with the "Dedicated
> hardware domain".
>
> Another solution, is rather than moving the devices in a separate domain,
> you move the toolstack. The latter may cause less trouble on platform
> without SMMU.
>
> Regards,
>
> --
> Julien Grall

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