[U-Boot] [PATCH v7 1/2] armv8: Support loading 32-bit OS in AArch32 execution state

[Ryan Harkin]

On 4 November 2016 at 15:53, Alexander Graf <agraf at suse.de> wrote:
>
>
> On 04/11/2016 16:43, york sun wrote:
>>
>> On 11/04/2016 09:32 AM, Ryan Harkin wrote:
>>>>>
>>>>>
>>>>> Yes, with the attached patch on top of your original 2 patches,
>>>>> everything works again.  I tested on FVP Foundation and AEMv8 models
>>>>> and Juno R0, R1 and R2.
>>>>>
>>>>> I don't think it would be good to stack these three patches the way
>>>>> they are presented in the upstream tree because it would not be
>>>>> bisect-able.  Some re-work or re-ordering would be needed.
>>>>>
>>>>> Note: I haven't attempted to understand what any of this code is
>>>>> doing, I'm just testing it with my standard boot flow to make sure
>>>>> nothing is broken for me.
>>>>
>>>>
>>>> Ryan,
>>>>
>>>> I support Alison's patch order for her 32-bit patch sets. This feature
>>>> doesn't exist before her first set. It is functional if you run U-Boot
>>>> at EL3 after the first patch.
>>>
>>>
>>> Which I don't do.  I follow the boot flow recommended by ARM and it
>>> doesn't work for that setup, which I don't think is the right thing to
>>> do.
>>>
>>>
>>>> It gets EL2 working after the 2nd set. If
>>>> there is room to clarify in the commit message, please kindly suggest.
>>>>
>>>
>>> Well, I'm not the maintainer of the tree, but I wouldn't want to have
>>> a tree that wasn't bootable at any point in the patch sequence.
>>> That's generally unacceptable on most projects I work on.  Keeping the
>>> tree bisect-able to prove which commit caused a problem is considered
>>> to be a valuable tool.
>>>
>>
>> Ryan,
>>
>> Thanks for sharing your concern. I support git-bisect. It is valuable,
>> no doubt. Let me try to understand the issue here. Without Alison's
>> patches, everything boots OK. With her first set, does something break?
>
>
> Yes, with the patches booting 64bit Linux with U-Boot running in EL2 breaks
> according to Ryan.
>
>> My understanding is 32-bit OS can boot. If existing 64-bit OS fails,
>> then she needs to fix it.
>
>
> That's his point :). And I concur.
>

Correct.  Thanks Alex for clarifying what I'm trying to say :)


> (btw, you guys really should start thinking about following the ARM
> recommended boot model. It's pretty cumbersome to do everything different
> just for NXP)
>