Re: [Xen-devel] [RFC PATCH v2] xen: arm: move rambase definitions to Rules.mk

[Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>]

Hi Ian,

OK. Thank you for your comment,

Regards,
Andrii

On Fri, Aug 22, 2014 at 7:05 PM, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> On Fri, 2014-08-22 at 14:09 +0300, Andrii Tseglytskyi wrote:
>> The reason of this pathch is the following - guest domain OS may
>> use iomem mappings. It is a typical way to handle devices in domU.
>> On some SoCs iomem starts from 0x40000000 base. Therefore it is
>> almost impossible to use iomem mappings, because it conflicts with
>> GUEST_RAM0_BASE pointer, which has similar value. Patch allows
>> to configure this from compile command line.
>>
>> Verified on OMAP5 with the following settings:
>> GUEST_CFG_RAM_BASE=0x80000000ULL GUEST_CFG_RAM_SIZE=0x80000000ULL
>
> I'm sorry but this approach is not going to fly. Apart from some debug
> functionality we do not want to be baking h/w specifics into the Xen
> binary at compile time.
>
> The correct solution to the problem you are trying to solve is to make
> the guest address space layout dynamic and settable by the toolstack,
> i.e. by providing a domctl to set the GIC and other base addresses on a
> per-domain basis (RAM I think is already handleable using
> populate_physmap).
>
> Ian.
>



-- 

Andrii Tseglytskyi | Embedded Dev
GlobalLogic
www.globallogic.com

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