[Arm-netbook] next step is a boot image

[Luke Kenneth Casson Leighton]

On Tuesday, January 17, 2023, Andreas Grapentin <andreas at grapentin.org>
wrote:
>
>
>> On 17. Jan 2023, at 11:10, Pablo Rath <pablo at parobalth.org> wrote:
>>
>> Ok. You are aware of that wiki page, are you?:
>> https://rhombus-tech.net/allwinner_a10/Buildroot_Toolchain/
>>
>> Once you have the toolchain running and a copy of legacy sunxi u-boot
>> make sure to checkout this tag:
>> git checkout v2013.07-sunxi.4
>>
>> make sure to change the boards.cfg (MMC_SUNXI_SLOT=2), and write sunxi
U-Boot to SD-Card with the commands described after v2013.07 or earlier.
This were the steps I had to take to boot a sunxi 3.4 kernel and a Debian
rootfs in 2020.
>> I have documented this here:
>> https://rhombus-tech.net/allwinner/a20/EOMA68-A20_2-7-4_preproduction/
>> (Section Sunxi U-Boot (legacy))
>>
>> If it helps, i could upload a copy of sunxi-spl.bin and u-boot.bin for
>> you.
>
> Thank you for those instructions, they were immensely helpful. I compiled
u-boot from the v2013.07-sunxi.4 tag, made the changes to the boards.cfg
you suggested, and deployed to SDcard, and the behaviour has changed. The
system now boot loops, repeating this output:
>
> U-Boot SPL 2013.07-07841-g569c37da7d-dirty (Jan 17 2023 - 19:37:10)
> Board: EOMA68_A20
> DRAM: 1024 MiB
> CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
> SUNXI SD/MMC: 0

okaay the SPL loader will now be trying to look on sd/mmc 0
for a u-boot image.  clearly it is not finding it.

and that's because sd/mmc 0 is routed to the microdesktop.
sd/mmc *3* is on the EOMA68-A20 Card.

which socket is the micro-sd card inserted in?
(and have you remembered to dd u-boot.bin onto it?)
and, did you fix the power issues which would allow
the MD SDcard Level Shifter to activate?

> for reference, this was the previous output:
>
>> U-Boot SPL 2017.01-2 (Jan 18 2017 - 21:30:38)
>> DRAM: 2048 MiB
>> CPU: 912000000Hz, AXI/AHB/APB: 3/2/2
>> Trying to boot from MMC2MMC Device 1 not found

yup there *is* no SD/MMC 1, u-boot-spl was compiled incorrectly
in this case.

>> spl: could not find mmc device. error: -19
>> SPL: failed to boot from all boot devices
>> ### ERROR ### Please RESET the board ###
>
> first thing I notice is that the reported CPU frequency and available RAM
is different.

not important.

> I wish that u-boot

... you are not yet *running* u-boot.  it is so big (1mb) it
cannot fit into 16k SRAM. the SPL loader initialises DDR3 memory
so that u-boot *can* be loaded into DRAM.

but you are not there yet.

>  would present me with a command line instead of resetting, but I haven’t
figured out how to do that yet.

the boot process is complex and multi-stage.
what the SPL loader is going into is a mere 16k SRAM.

there is absolutely flat-out zero chance of getting a
"prompt" in the *SPL* loader.

in 2nd stage - actual u-boot - not a problem at all.

l.


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