[PATCH 2/2] ARM: axxia: remove TEXT_OFFSET override hack

[Alexander Sverdlin]

Hi Ard,

On 12/01/2021 11:40, Ard Biesheuvel wrote:
>>> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
>>> ---
>>>  arch/arm/Makefile | 1 -
>>>  1 file changed, 1 deletion(-)
>>>
>>> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
>>> index 4aaec9599e8a..c0496983198f 100644
>>> --- a/arch/arm/Makefile
>>> +++ b/arch/arm/Makefile
>>> @@ -151,7 +151,6 @@ textofs-$(CONFIG_ARCH_IPQ40XX) := 0x00208000
>>>  textofs-$(CONFIG_ARCH_MSM8X60) := 0x00208000
>>>  textofs-$(CONFIG_ARCH_MSM8960) := 0x00208000
>>>  textofs-$(CONFIG_ARCH_MESON) := 0x00208000
>>> -textofs-$(CONFIG_ARCH_AXXIA) := 0x00308000
>>>
>>>  # Machine directory name.  This list is sorted alphanumerically
>>>  # by CONFIG_* macro name.
>> What should the users of uncompressed kernel do with their legacy bootloaders?
>> I've tested you patch and AXXIA bootloader is not able to deal with 0x8000 default
>> load address...
>>
> I am not sure I understand why this makes a difference. Does the AXXIA
> bootloader take the load address from the uncompressed image somehow?
> 
> I would assume that the bootloader knows about the memory reservation
> at the base of DRAM, and places the kernel image outside of it. That
> kernel image can now run at any offset of the start of DRAM modulo 2
> MB.
> 
> Maybe the issue is that the old offset is 3 MiB?

Some more info from the AXXIA U-Boot, include/configs/axxia.arm.h:

#define CONFIG_UBOOT_REGION_SIZE        0x400000
#define CONFIG_FEMAC_DMA_SIZE           0x40000
#define CONFIG_FEMAC_DMA_START          (CONFIG_UBOOT_REGION_SIZE - CONFIG_FEMAC_DMA_SIZE)

>From what I see in same file the layout seems to be:
Start: 0
CodeEnd: 0x200000
StackTop: 0x260000
HeapTop: 0x3C0000
FEMAC_Top: 0x400000

So the previous 0x308000 worked overwriting U-Boot heap, but
going down to 0x8000 actually overwrites U-Boot code and everything explodes...

-- 
Best regards,
Alexander Sverdlin.