Zyxel "firmware" format is just… a FIT with some metadata on the models.
This FIT is like this:
--------------------------
uImage FIT header
--------------------------
Linux kernel
--------------------------
FDT DTB
--------------------------
Padding so that
this makes
8192kb [1]
--------------------------
UBI volume
as a root filesystem
--------------------------
We just reproduce this in a very brutal and naive way.
In the future, this seems worth to generalize and modularize this idea
so that zyxel-nwa-fit is just an instance of a more general output.
[1]: https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/ramips/image/mt7621.mk;h=ab1b829ba0086cb9fc9ca8cbbf3cbc14735034d6;hb=refs/heads/main#l3097
Signed-off-by: Raito Bezarius <masterancpp@gmail.com>
I believe there should be another module exposing `rootubifs` as `rootfs`
or let any other module just subsume that component like `zyxel-nwa-fit` output.
Signed-off-by: Raito Bezarius <masterancpp@gmail.com>
Some devices have a U-boot variant that does not accept a third
parameter on the "bootm" command, meaning we can't override the dtb
in the bootloader so have to smush it back into the kernel image
This doesn't work in QEMU but I think the problem is with the
U-Boot configuration for QEMU. It does work on at least one
hardware device so I'm pushing it anyway
Based on
https://gti.telent.net/raboof/liminix/src/branch/tftp-old-uboot
Co-authored-by: Arnout Engelen <arnout@bzzt.net>
Adding the reserved-memory node to the dtb can cause it to grow
by enough that it needs an extra page - this will overlap the start
of the kernel image if we calculate offsets based on the original size
Reported-by: sinavir
Authored-by: sinavir
new layout has rootfs followed by kernel and dtb, so that we
know the rootfs start and size to embed them into the dtb instead
of having to use dummy values and fill them in afterwards
This is for QEMU where we won't have to provide a dtb because the
device tree is built by the platform according the (emulated) hardware
present.
Maybe in future there will be other hardware devices where we
don't need to provide a dtb.
