On 1/13/26 11:25 AM, Beleswar Prasad Padhi wrote:
- Should mkimage -E align blobs to 8 bytes by default ? I think yes,
and frankly, I thought it does so already, but apparently not.
This can be done, but should it be? Not all FITs demand an 8-byte
alignment right? It is only the FDT which requires this.
Maybe if image type is flat_dt, it should be implicitly 8-byte aligned then
?
Well, the device tree spec says 8-byte alignment.
8 byte alignment of what, start of DT, right ?
Yeah from start... In this case, the FDT for OS is aligned, but the sub DT
from the FIT is not aligned by 8-bytes.
For mkimage -E (fit with trailing external data) , enforcing that
alignment should be easily doable.
It's not "FDT for OS"
that's 8-byte, it's any device tree should start out 8 byte aligned, and
everything else should then be naturally aligned. If we're looking in a
device tree for another device tree to use in place and not relocate
then that second tree must be aligned.
Or am I missing something?
The discussion is about mkimage -E which generates DTs for U-Boot SPL use. The
DTs in those external data should likely be aligned to 8 bytes by default, i.e.
implicitly set -B 8 (they don't seem to be right now).
Instead of -E, we can use '-b' which always takes DT and make sure that is
8-byte aligned by default:
Usage: mkimage [-D dtc_options] [-f fit-image.its|-f auto|-f auto-conf|-F] [-b <dtb> [-b
<dtb>]] [-E] [-B size] [-i <ramdisk.cpio.gz>] fit-image
-b => append the device tree binary to the FIT
The type flat_dt should likely always be implicitly aligned at minimum
to 8 bytes , without -b or -B or -whatever flags.
--
Best regards,
Marek Vasut
