Re: [Qemu-devel] [RFC v1 2/2] arm: boot: Add EL jump-down code for Linux

[Peter Crosthwaite]

On Tue, Sep 2, 2014 at 3:15 AM, Peter Maydell <address@hidden> wrote:
> On 19 August 2014 01:54, Peter Crosthwaite <address@hidden> wrote:
>> Linux should boot in EL2 or EL1. If in EL3, jump down before handing
>> off to Linux.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>
> The other way we could do this would be to have the
> do_cpu_reset() hook put the CPU into EL2 or EL1 before
> starting the boot code. (This would be in line with how it
> would work for KVM).
>

Tried that at first, and the problem we found was it introduced a
reset order dep. The arm-boot and CPU race on who sets the EL.

> Have you thought about how this would work for
> secondary CPUs (which boot via PSCI poweron)?
>

Not yet although I expect something similar. Currently I use a spin
table elf which I load and entry-points for the secondaries (I have a
bootloader patch out-of-tree that can do this) which does the
reduction. It's pretty much the same routine as here so there might be
some code share.

Regards,
Peter

> thanks
> -- PMM
>