[PATCH 07/10] Makefile: Align fit-dtb.blob and u-boot.itb by 64bits for 64bit systems

[Michal Simek]

On 8/19/21 6:18 PM, Tom Rini wrote:
> On Thu, Aug 19, 2021 at 06:01:39PM +0200, Michal Simek wrote:
>> Hi Andre,
>>
>> On 8/19/21 5:56 PM, Andre Przywara wrote:
>>> On 8/19/21 12:19 PM, Michal Simek wrote:
>>>
>>> Hi,
>>>
>>>> Enabling MULTI_DTB_FIT and DTB_RESELECT can end up with multi DTBs in FIT
>>>> image placed and aligned only by 32bits (4bytes). For 64bit systems there
>>>> is 64bit (8bytes) alignment required. That's why make sure that
>>>> fit-dtb.blob and u-boot.itb as our primary target images for Xilinx
>>>> ZynqMP
>>>> are all 64bit aligned. The patch is using CONFIG_PHYS_64BIT macro to
>>>> identify 64bit systems (including 32bit systems with PAE).
>>>>
>>>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>>>> ---
>>>>
>>>>   Makefile | 7 +++++++
>>>>   1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/Makefile b/Makefile
>>>> index 269e353a28ad..1bbe95595efe 100644
>>>> --- a/Makefile
>>>> +++ b/Makefile
>>>> @@ -1169,6 +1169,10 @@ MKIMAGEFLAGS_fit-dtb.blob = -f auto -A $(ARCH)
>>>> -T firmware -C none -O u-boot \
>>>>       -a 0 -e 0 -E \
>>>>       $(patsubst %,-b arch/$(ARCH)/dts/%.dtb,$(subst
>>>> ",,$(CONFIG_OF_LIST))) -d /dev/null
>>>>   +ifeq ($(CONFIG_PHYS_64BIT),y)
>>>
>>> Why is this restricted to 64-bit "systems"? The DT spec[1] clearly
>>> states that some DT parts (/memreserved/ block, for instance), must be
>>> 64-bit aligned, which means the whole blobs needs to be 64-bit aligned.
>>> Granted this probably does not cause real issues on 32-bit systems, but
>>> is violating the spec anyway.
>>> So I'd say we add the alignment requirement unconditionally.
>>
>> That's even better for me and we need to make sure that dtbs itself are
>> aligned and also dtbs inside FIT image are aligned too.
> 
> Right, all dtbs need to be 8 byte aligned to start with.  Enforcing this
> is what will unblock moving to a newer libfdt where that's checked for
> up-front now.
> 

As is in the second thread. Does it make sense to also align the end?
I did that in 8/10 patch.
The problem with these alignments is that you also need to align the
start of FIT image. Maybe would the best to copy fdt to different
aligned location.

Thanks,
Michal