On 11/26/21 4:36 PM, Abder wrote:
Hi Alex,
Just a quick remarque that intrigued me:
Le jeu. 25 nov. 2021 à 15:57, Alex G. <mr.nuke...@gmail.com> a écrit :
On 11/25/21 1:07 AM, Chan Kim wrote:
Hello all,
I'm trying to implement falcon mode for our board. Then should I first
implement the normal mode(spl + proper)?
It looks like so while I'm reading doc/README.falcon. (It says, after
loading kernel, DT etc. I should give 'spl export' command).
Falcon mode is a bit board dependent. There are a couple of ways you
could go about this.
The first is to have an "fdtargs" partition. This is where "spl export"
comes in. Once you run "spl export", it will give a modified dtb at
"$fdtargsaddr". It's that DTB that you need to write to your ftdargs
partition. For example:
> spl export fdt $loadaddr - $fdt_addr_r
> mmc write $fdtargsaddr 0x9800 0x8000
In this example the ftdargs partition starts at sector 0x9800, and is
0x800 sectors long.
The second option is to forget about "spl export" and "fdtargs", and
package your kernel, devicetree, and overlays in a FIT container. You'd
make sure to enable SPL_LOAD_FIT_APPLY_OVERLAY. There isn't much more to
this other than the usual gotcha's with FIT and overlays.
Do you mean by this that the SPL has the capability to generate the
"fdtargs" by it self (if we provide it with the dtb in the fitImage) ?
Form my last experience with the falcon mode, I had a - not sure -
conclusion that the only way to generate the "fdtargs" is by using the
"spl export" command from uboot cmdline !
because the reality of the fdtargs blob, as its name indicates, is not
just the fdt but it has also the bootargs (inside the chosen node )
that are required by the kernel. So if you give only the DTB to the
SPL it will not work - to my knowledge -, cuz the data that will be
passed to the kernel needs to contain also the bootargs !
Can you please confirm to me if this capability is implemented on the
SPL and that we can actually forget about the "spl export" command ?
It might not be obvious that an overlay can contain the "/chosen" node
with the appropriate bootargs:
/dts-v1/;
/plugin/;
/ {
fragment@1 {
target-path = "/chosen";
__overlay__ {
bootargs = "root=blablabla console=ttyeS0";
};
};
};
Thanks
And apologies Chan for jumping on your thread,
Best regards,
--
Abder
