Re: [PATCH RFC 0/N] xen: arm: rework early bring up

[Julien Grall <julien.grall@linaro.org>]

Adding Andre,

On 09/17/2013 02:37 AM, Ian Campbell wrote:
> Hi,

Hi,

> The following reworks early bring up on ARM to use a separate set of
> boot pagetables. This simplifies things by avoiding the need to bring up
> all CPUs in lock step, which in turn allows us to do secondary CPU
> bringup in C code.

Great ! I will give a try on different boards and see what happens.

> Unfortunately the main bulk of this change is a single large patch which
> is hard to decompose any further since it is basically pulling on the
> thread and then knitting a new jumper from it.

I think you can split the patch in:
   - Add the new platform callback
   - Fast model SMP code
   - ...

We will have dead code for "few" commit in Xen, but it will be easier to 
read the patch series :).

> With these changes Xen now absolutely requires that the bootloader calls
> the hypervisor in HYP mode, the previous workarounds have been removed.
> For use on models a bootwrapper is now required. See
>          git://xenbits.xen.org/people/ianc/boot-wrapper.git xen-arm32
>          git://xenbits.xen.org/people/ianc/boot-wrapper-aarch64.git xen-arm64
>
> I have implemented support for CPU bringup on the fastmodel vexpress
> platforms (v7and v8) here, I suppose it should work OK on a real
> vexpress too but I've not tried it.

Unfortunately on the versatile express there is 2 different ways to 
bring up CPUs.
We can stick to this CPU bring up, as long as we ask the user to modify 
the board configuration.

> I'm hoping that those of you with access to other platforms will
> implement the required cpu_up platform hook, it should be pretty simple
> in each case, I think.
>
> It should now also be possible to implement PSCI, but I have not done
> so.
>
> Ian
>
>
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-- 
Julien Grall