[U-Boot] merge arm64 to arm

[Måns Rullgård]

Tom Rini <trini at ti.com> writes:

> On 08/19/2013 01:33 PM, Måns Rullgård wrote:
>> Scott Wood <scottwood at freescale.com> writes:
> [snip]
>>> i960 is a bad analogy.  It's often possible to turn arm32 asm
>>> into arm64 asm with some search and replace and minor manual
>>> fixups.
>>
>> Only if the original uses none of the distinguishing features of
>> ARM like predicated instructions or variably shifted operands.
>> Once you limit yourself to the remaining basic operations, every
>> (RISC) architecture looks the same.
> [snip]
>> AArch64 of course shares certain non-ISA aspects with AArch32.
>> Page table formats and other architecturally defined system control
>> features are the same, and code for managing these things should of
>> course be shared.  Some other features, e.g. exception handling,
>> are different enough that sharing code is probably difficult.
>>
>> There is a tendency to see arm64/aarch64 as yet another 64-bit
>> extension of a 32-bit architecture, which it is not.  Assuming that
>> software support will or can follow the model used by the others
>> mentioned is thus a mistake.
>
> We don't have lots of hand-crafted assembly, and what we do, we
> largely have split out already into the cpu directories.  I really
> think we just need to try this and see how it goes.

Fine, let's see what it ends up looking like.

That said, please consider naming things in a way that armv8 does not
imply 64-bit.

-- 
Måns Rullgård
mans at mansr.com