Re: [PATCH 9/9] [DNI] ARM: multi_v7_defconfig: Enable CONFIG_ARM_LPAE for multi_v7_config

Arnd Bergmann
2023-01-19T15:11:39Z

On Thu, Jan 19, 2023, at 15:42, Alexander Stein wrote:
> This is necessary to support PCIe on LS1021A.
>
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>

Can you explain why this is actually required? I can see that the
ranges in the PCIe device point to a high address (0x4000000000,
2^40), but I can't tell if this is hardwired in the SoC or a
setting that is applied by software (either the bootloader or
the PCIe driver).

If you can reprogram the memory map, I would expect this to fit
easily into the 32-bit address space, with 1GB for DDR3 memory
and 1GB for PCIe BARs.

I don't mind having a defconfig with LPAE enabled, I think this
can be done using a Makefile target that applies a config
fragment on top of the normal multi_v7_defconfig, you can find
some examples in arch/powerpc/configs/*.config.

Arnd