[U-Boot] [PATCH v4 26/26] sunxi: A64: add 32-bit SPL support

[Simon Glass]

Hi Andre,

On 2 January 2017 at 04:48, Andre Przywara <andre.przywara at arm.com> wrote:
> When compiling the SPL for the Allwinner A64 in AArch64 mode, we can't
> use the more compact Thumb2 encoding, which only exists for AArch32
> code. This makes the SPL rather big, up to a point where any code
> additions or even a different compiler may easily exceed the 32KB limit
> that the Allwinner BROM imposes.
> Introduce a separate, mostly generic sun50i-a64 configuration, which
> defines the CPU_V7 symbol and thus will create a 32-bit binary using
> the memory-saving Thumb2 encoding.
> This should only be used for the SPL, the U-Boot proper should still be
> using the existing 64-bit configuration. The SPL code can switch to
> AArch64 if needed, so a 32-bit SPL can be combined with a 64-bit U-Boot
> proper to eventually launch arm64 kernels.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
>  board/sunxi/Kconfig            | 14 ++++++++++++--
>  configs/pine64_plus_defconfig  |  2 +-
>  configs/sun50i_spl32_defconfig | 10 ++++++++++
>  3 files changed, 23 insertions(+), 3 deletions(-)
>  create mode 100644 configs/sun50i_spl32_defconfig

Following up on the previous discussion, I take it that one on problem
is that U-Boot does not support building SPL with one toolchain and
U-Boot proper with another?

Re wanting to build SPL either as 32-bit or 64-bit, could this be a
Kconfig option perhaps?

Anyway, if this is what we have for now, fine. But I'd like to see at
least a TODO suggesting a better solution.

Regards,
Simon