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

[Tom Rini]

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.

-- 
Tom
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