[Letux-kernel] jz4730-i2c - clocksource

H. Nikolaus Schaller hns at goldelico.com
Sun Mar 7 19:54:54 CET 2021

Hi Paul,

> Am 07.03.2021 um 19:22 schrieb Paul Boddie <paul at boddie.org.uk>:
> On Sunday, 7 March 2021 18:11:42 CET H. Nikolaus Schaller wrote:
>> Ah, I see. The legacy u-boot does neither support loading DTB nor is it able
>> to uncompress bigger uImages.
> I tried to configure the kernel to do something sensible with appended DTB 
> files, but that didn't make any difference.

This didn't work either for me... And it makes the uncompress size limit even
a bigger problem.

I had found in Sept/Oct 2020 or so that by removing more and more config options
and at ca. 3.8 MB uImage size the kernel did load.

>> This is why I use the two-staged approach where legacy u-boot loads the
>> new u-boot by Ludomir which then can do everything. Loading bootargs.scr
>> is done by a boot.scr that I provide.
>> I think this is the reason why I have named it "Image". Because
>> legacy-u-boot has hard-coded to load an "uImage". So the second phase
>> u-boot is called "uImage" and that it does not try to load itself the
>> kernel is named "Image".
> That would make sense. How do you build U-Boot for SD card deployment? I only 
> see a configuration for NAND:
> configs/alpha400_nand_defconfig

Yes, i use this, although it was originally intended for NAND.
It is the u-boot that was provided by Lubomir Rintel a while ago.

No changes, except adding the boot.scr.

> [...]
>> Ah, sorry.
>> That was an older /boot without having mounted the FAT
>> partition. The FAT partition looks like:
>> root at letux:~# ls -lR /boot
>> /boot:
>> total 5880
>> -rwxr-xr-x 1 root root 5233921 Mar  7  2021 Image
>> -rwxr-xr-x 1 root root      79 Mar  7  2021 Image.info
>> -rwxr-xr-x 1 root root    2156 Jan 31  2021 boot.scr
>> -rwxr-xr-x 1 root root    2108 Mar  7  2021 bootargs.scr
>> drwxr-xr-x 2 root root    8192 Mar  7  2021 ingenic
>> -rwxr-xr-x 1 root root     843 Jan 31  2021 makesd.info
>> -rwxr-xr-x 1 root root  500979 Jan 31  2021 u-boot.bin
>> -rwxr-xr-x 1 root root  234810 Jan 31  2021 uImage
> OK, this makes more sense now.
>> /boot/ingenic:
>> total 16
>> -rwxr-xr-x 1 root root 12078 Mar  7  2021 alpha400.dtb
>> root at letux:~#
>> here we see that both, uImage and Image exist plus
>> the u-boot.bin for the second phase U-Boot.
>> And I have a boot.scr (for the second phase u-boot)
>> which loads DTB and Image and runs bootargs.scr before
>> starting the kernel:
>> 	https://download.goldelico.com/letux-u-boot/Mipsbook400/latest/
> I guess I could use the CONFIG provided here to reproduce the build.
>> I have developed that once last year and the boot process
>> is a "never touch a running system unless absolutely necessary"
>> thing for me :)
> Sure. That is why I had been hoping to use the existing U-Boot, which I guess 
> I still can, but now with another U-Boot to actually load the kernel.

Yes, that is the strategy I had developed last year to get the
Letux 400 boot a newer kernel.

Alternatively you can just throw my existing binaries on some SD card
and focus on modifying the kernel.

IMHO there is not much to gain by redoing the same u-boot mistakes :)
Although it may give freedom to do other analyses later.

But from the point we were able to boot from MMC to a "login:"
I never wanted to go back (and AFAIR I haven't looked into
any u-boot code any more)... It "just works".


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