On 11/26/21 1:53 AM, Chan Kim wrote:
Hi Alex,
Thanks for the reply.
So I gather that to be able to use 'spl export fdt' to store the 'snapshot' to
the storage I should make the spl program runnable at least to that stage.
(being able to load kernel image, dtb, initrd and give the spl export command
to capture it to storage like SD card).
What I'm thinking of is to let another processor(cortext-M7 based scp, system
control processor) load the u-boot-spl.bin into on-chip RAM and
kernel(including initramfs)and dtb into SDRAM all from SD card (RAW mode, no
file system) and let the AP(application processor) start from u-boot-spl.bin.
In this scheme u-boot-spl doesn't need to load anything and DRAM is already
initialized and it just needs to run from kernel image after very minimal setup
(passing kernel arguments). Do you think this is possible or an absurd idea?
Any comment will be a big help for me.
I'm not sure if that mode is currently supported. You could try using
CONFIG_SPL_RAM_SUPPORT=y, and one of two things:
a) Package your kernel and DTB in a FIT.
b) Extend common/spl/spl_ram.c to support the 'snapshot' dtb
Alex
Thanks!
Chan
-----Original Message-----
From: Alex G. <mr.nuke...@gmail.com>
Sent: Thursday, November 25, 2021 11:57 PM
To: Chan Kim <c...@etri.re.kr>; U-Boot Mailing List <u-boot@lists.denx.de>
Subject: Re: a question about falcon mode
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.
Alex
