Re: [PATCH v2 2/2] ARM: OMAP2+: Pad SPL binary to 8-byte alignment before DTB

[Marek Vasut <marek.vasut@mailbox.org>]

On 1/12/26 5:48 PM, Tom Rini wrote:
> On Mon, Jan 12, 2026 at 06:38:19PM +0530, Anshul Dalal wrote:
>> On Mon Jan 12, 2026 at 3:41 PM IST, Beleswar Padhi wrote:
>>> The OMAP2 SPL linker script (also used for K3 platforms) currently uses
>>> a 4-byte alignment directive after the __u_boot_list section. This
>>> alignment directive only advances the location counter without padding
>>> the actual binary output.
>>>
>>> When objcopy extracts u-boot-spl-nodtb.bin, it includes only actual
>>> data, stopping at the last byte of __u_boot_list (e.g., 0x41c359fc),
>>> not an aligned address (e.g., 0x41c35a00). So, when the FIT image
>>> containing device trees is concatenated to the SPL binary, it gets
>>> appended at this unaligned file size, causing libfdt validation failure.
>>>
>>> To fix this, move the alignment directive into the __u_boot_list section
>>> itself and make it 8-byte aligned as per DT spec. This forces the linker
>>> to include padding as part of the section data, ensuring objcopy
>>> includes the padding bytes in the binary and the appended FIT image
>>> starts at an 8-byte aligned boundary.
>>>
>>> Reported-by: Anshul Dalal <anshuld@ti.com>
>>> Closes: https://lore.kernel.org/u-boot/DFJ950O0QM0D.380U0N16ZO19E@ti.com
>>> Fixes: 0535e46d55d7 ("scripts/dtc: Update to upstream version v1.7.2-35-g52f07dcca47c")
>>> Signed-off-by: Beleswar Padhi <b-padhi@ti.com>
>>> ---
>>> v2: Changelog:
>>> 1. Get rid of extra ALIGN() directive, replace it with a comment
>>> 2. Carry Reported-by, Closes and Fixes tag.
>>>
>>> Link to v1:
>>> https://lore.kernel.org/all/20260109190026.58464-3-b-padhi@ti.com/
>>>
>>>   arch/arm/mach-omap2/u-boot-spl.lds | 6 +++++-
>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/u-boot-spl.lds b/arch/arm/mach-omap2/u-boot-spl.lds
>>> index 3bb759d8a1c..5ad169a37b7 100644
>>> --- a/arch/arm/mach-omap2/u-boot-spl.lds
>>> +++ b/arch/arm/mach-omap2/u-boot-spl.lds
>>> @@ -35,9 +35,13 @@ SECTIONS
>>>   	. = ALIGN(4);
>>>   	__u_boot_list : {
>>>   		KEEP(*(SORT(__u_boot_list*)));
>>> +		/*
>>> +		 * Ensure 8-byte alignment at the end of the last section before
>>> +		 * DTB is appended, to satisfy DT spec alignment requirements
>>> +		 */
>>> +		. = ALIGN(8);
>>
>> I wonder if there could be a better way to handle this constraint,
>> currently we have two major problems with this approach:
>>
>> 1. All platforms facing similar alignment issues would have to modify
>> their linker scripts.
> 
> Yes, agreed.
> 
>> 2. The FDT only gets appended directly to SPL binary in cases of
>> CONFIG_SPL_SEPARATE_BSS. Otherwise we do (SPL binary + BSS + FDT) as per
>> the $(obj)/$(SPL_BIN)-dtb.bin make target. Which means BSS would have to
>> be 8-byte aligned as well as the SPL binary.
>>
>> I wonder if we could have a new make target for say
>> u-boot-spl-nodtb-aligned.bin which is just (SPL binary + optionally BSS
>> + padding for alignment) and at runtime we modify the fdt addr in gd to
>> point to the correctly aligned address?
> 
> Looking back at
> https://lore.kernel.org/all/87h65ihumb.fsf@bloch.sibelius.xs4all.nl/ we
> can use dd as a portable way to ensure that a file ends with 8-byte
> alignmnent by doing:
> dd if=testfile bs=8 conv=sync of=testfile_pad
> and we get a zero-padded 8-byte aligned output file, and at the end of
> that we can concatenate our dtb.
You still need to make sure there is a symbol generated by the linker 
that points at the END of the u-boot binary . dd happens too late, so 
you cannot do that. The alignment has to be done by the linker, in the 
linker script I think.