[PATCH] riscv: Only enable OF_BOARD_FIXUP for S-Mode

[Sean Anderson <seanga2@gmail.com>]

On 9/6/20 7:18 AM, Heinrich Schuchardt wrote:
> On 9/5/20 3:22 PM, Sean Anderson wrote:
>> It is unsafe to enable OF_BOARD_FIXUP only based on OF_SEPARATE.
>> OF_SEPARATE may indicate that the user wishes U-Boot to use a different
>> device tree than one obtained via OF_PRIOR_STAGE. However, OF_SEPARATE may
>> also indicate that the device tree which would be obtained via
>> OF_PRIOR_STAGE is invalid, nonexistant, or otherwise unusable. In this
>> latter case, enabling OF_BOARD_FIXUP will result in corruption of the
>> device tree. To remedy this, only enable OF_BOARD_FIXUP if U-Boot is
>> configured for S-Mode.
>>
>> Fixes: 1c17e55594a394ced7de88d91be294eaf8c564c1
>> Signed-off-by: Sean Anderson <seanga2@gmail.com>
>> ---
>>
>>  arch/riscv/Kconfig | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 009a545fcf..13fac51483 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -288,6 +288,6 @@ config STACK_SIZE_SHIFT
>>  	default 14
>>
>>  config OF_BOARD_FIXUP
>> -	default y if OF_SEPARATE
>> +	default y if OF_SEPARATE && RISCV_SMODE
> 
> 
> OF_BOARD_FIXUP is also defined in dts/Kconfig.
> Moving the "default" line to dts/Kconfig would simplify the code.

Probably.

> 
> Why do we need the dependency on OF_SEPARATE? Isn't RISCV_SMODE enough?

Because there is no need to do this fixup if we are using sbi's device
tree. From the commit referenced above:

> Starting from OpenSBI v0.7, the SBI firmware inserts/fixes up the
> reserved memory node for PMP protected memory regions. All RISC-V
> boards need to copy the reserved memory node from the device tree
> provided by the firmware to the device tree used by U-Boot.

--Sean