[PATCH] arm: relocate: Introduce data-only relocation mode

[Marek Vasut]

On 3/29/26 12:00 AM, Tom Rini wrote:
> On Sat, Mar 28, 2026 at 01:03:15AM +0100, Marek Vasut wrote:
>> On 3/16/26 6:10 PM, Tom Rini wrote:
>>
>> Hello Tom,
>>
>>>>>> +config SKIP_RELOCATE_CODE
>>>>>> +	bool "Skips relocation of U-Boot code to end of RAM"
>>>>>> +	help
>>>>>> +	  Skips relocation of U-Boot code to the end of RAM, but still does
>>>>>> +	  relocate data to the end of RAM. This is mainly meant to relocate
>>>>>> +	  data to read-write portion of the RAM, while the code remains in
>>>>>> +	  read-only portion of the RAM from which it is allowed to execute.
>>>>>> +	  This split configuration is present on various secure cores.
>>>>>
>>>>> Is this really configurable, or is this determined by the SoC? This
>>>>> feels like something a board should be select'ing rather than
>>>>> configuring and I do worry about boards abusing this in the same of some
>>>>> possibly dubious speed-up rather than the intented and valid use case.
>>>>
>>>> On R-Car X5H, the Cortex-M core U-Boot port selects this, the Cortex-A core
>>>> U-Boot port does NOT select this. So, this is neither SoC level
>>>> configuration nor board level configuration, this is SoC CPU core level
>>>> configuration. I can definitely hide this symbol and conditionally select it
>>>> on SoC level.
>>>
>>> At the high level, this sounds similar to the TI K3 platforms where we
>>> have a Cortex-R build and a Cortex-A build and so (ARCH_K3 && CPU_V7R)
>>> is valid in Kconfig. I assume there something similar in this situation,
>>> so yes please, thanks.
>>>
>>>>> [snip]
>>>>>> diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
>>>>>> index 6ee58f4edfe..b6a648708f4 100644
>>>>>> --- a/arch/arm/lib/relocate.S
>>>>>> +++ b/arch/arm/lib/relocate.S
>>>>>> @@ -79,6 +79,15 @@ ENDPROC(relocate_vectors)
>>>>>>     ENTRY(relocate_code)
>>>>>>     relocate_base:
>>>>>>     	adr	r3, relocate_base
>>>>>> +
>>>>>> +#ifdef CONFIG_SKIP_RELOCATE_CODE
>>>>>> +	mov r4,	#CONFIG_SKIP_RELOCATE_CODE_DATA_OFFSET
>>>>>
>>>>> Spacing. But if there's no other comments and propmting the user is
>>>>> correct, I can fix when applying.
>>>> Fixed in V2 .
>>>
>>> Thanks.
>> Either drop this patch and wait for V2, or I will send a follow up ?
> 
> Sigh, I forgot about my own feedback here even, I'll revert this in next
> shortly, sorry.
I can also send a follow up fix, which I already have in tree for this.