[U-Boot] [RFC PATCH 0/2] ARMv8 Aarch32 support

[Tom Rini <trini@konsulko.com>]

On Fri, Dec 02, 2016 at 11:51:07AM +0000, Ryan Harkin wrote:

> I've been working with Soby Mathew to get U-Boot booting on ARM's
> AEMv8 FVP model in Aarch32 mode.
> 
> Soby worked out what needed to be changed and I'm refining the changes
> into patches that can be built for both Aarch64 and Aarch32 mode.
> 
> There are two patches for discussion:
> 
> [RFC PATCH 1/2] Add Aarch32 option for ARMv8 CPUs
> [RFC PATCH 2/2] Add vexpress_aemv8a_aarch32 variant
> 
> I expect the first patch to be controversial.  I also don't expect it to 
> be accepted, but to demonstrate what changes we needed to make to get an 
> ARMv8 platform to boot in Aarch32 mode when selecting CPU_V7 instead of
> ARM64 as the CPU type.  This in itself may be the wrong approach.
> 
> It adds an ARMV8_AARCH32 config option and some checks in generic code 
> for that option to allow the code to differentiate between the two
> modes.
> 
> The second patch should be less controversial.  It adds support for a
> new AEMv8 variant that runs in 32-bit mode.  The most awkward part is
> that it defines itself not as ARM64, but as CPU_V7.  I expect this to
> change based on feedback from patch 1/2.
> 
> The Aarch32 code runs on the same AEMv8 model as the Aarch64 code, but 
> takes an extra per-core model launch parameter to switch the cores into
> Aarch32 mode, eg. "-C cluster0.cpu0.CONFIG64=0".

So my first and slightly ignorant question is, why isn't this just a new
regular ARMv7 board being added rather than a special cased ARMv8?

-- 
Tom
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