[U-Boot] ARMv8: Use U-Boot to boot Xen?

[Dirk Behme <dirk.behme@gmail.com>]

On 29.01.2016 10:18, Ian Campbell wrote:
> On Fri, 2016-01-29 at 12:04 +0800, Peng Fan wrote:
>> Hi Dirk,
>>
>> Cc Ian xen experts.
>>
>> On Thu, Jan 28, 2016 at 08:06:30PM +0100, Dirk Behme wrote:
>>> Hi,
>>>
>>> are there any U-Boot examples/patches to boot Xen on an ARMv8/aarch64
>>> system?
>>>
>>> I've found
>>>
>>> http://lists.denx.de/pipermail/u-boot/2015-October/230077.html
>>>
>>> what might be helpful.
>>>
>>> But maybe I missed anything else?
>>
>> I guess you are asking steps how to boot xen using uboot?
>>
>> You may need to take this:
>> http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions
>
> Indeed.
>
> In addition one AArch64 system which uses u-boot and which has concrete
> instructions is the APM X-Gene/Mustang:
>      http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/APMXGeneMustang
> which would likely be helpful.


Yes, that page is very helpful, thanks!

But I think it misses one information, or most probably the 
configuration on that board is different. Above page just do a 'run 
xen_run' which in the end does the necessary tftp loading and finally 
the bootm to start Xen.

So I'd assume that on that board U-Boot runs at EL3 or EL2 (?).

In my environment, U-Boot runs at EL1. I.e. after loading Xen by tftp 
I somehow need to switch to EL2 to be able to start Xen.

And this is what I think I miss. How to switch from U-Boot running at 
EL1 to hypervisor mode EL2? Therefore I'd think that

http://lists.denx.de/pipermail/u-boot/2015-October/230077.html

might be helpful.

Best regards

Dirk