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

[Ian Campbell <ian.campbell@citrix.com>]

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.