Last supported kernel AT91SAM9G20

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danybd
Posts: 3
Joined: Tue Nov 17, 2020 8:01 pm

Last supported kernel AT91SAM9G20

Wed Nov 18, 2020 8:40 pm

Hello everybody,

currently I am trying to build the kernel for a legacy board, just as personal educational task.
https://www.acmesystems.it/FOXG20
I´ve never build a linux from scratch and I thought this would be a nice project to start with. I already build a kernel using the an adapted configuration for this board. My problem is the kernel does not boot. Somehow my bootloader does not recognize that I have placed a new kernel in the SD card and I am starting to wonder if the last relesed kernel version is supported by this chip. Could please somebody with more experience provide me some advice? I´ve been working on this for several days and starting to get frustrated.
There is no much documentation where I can get some help from, probably because it is a legacy system.
Regards
Daniel
blue_z
Location: USA
Posts: 2131
Joined: Thu Apr 19, 2007 10:15 pm

Re: Last supported kernel AT91SAM9G20

Thu Nov 19, 2020 2:10 am

The ARM 926EJ-S processor and AT91SAM9G20 SoC are actively supported in the Linux kernel.
There has been a Device Tree file in mainline for the FoxG20 board since version 3.11.
Since there is a at91-foxg20.dts in the pending 5.10 release, there is no "last" kernel.

Regards
danybd
Posts: 3
Joined: Tue Nov 17, 2020 8:01 pm

Re: Last supported kernel AT91SAM9G20

Thu Nov 19, 2020 8:11 pm

Thank you for the reply! Then I wonder why is my kernel not booted by the bootloader. The last kernel provided by the board producer is an Uimage and there is no device tree. Is it because kernel 2.6 had no device tree?
Do I need maybe a new bootloader? I supposed if my bootloader works with 2.6 should wirh 5.X too. Am I wrong?
Regards
Daniel
blue_z
Location: USA
Posts: 2131
Joined: Thu Apr 19, 2007 10:15 pm

Re: Last supported kernel AT91SAM9G20

Fri Nov 20, 2020 12:42 am

danybd wrote: Then I wonder why is my kernel not booted by the bootloader. The last kernel provided by the board producer is an Uimage [sic] and there is no device tree. Is it because kernel 2.6 had no device tree?
Do I need maybe a new bootloader?
You provide just a few ambiguous details. We can't read your mind and don't have access to your code.
With such scant information I'm not going to bother to speculate.
A description of the components involved, a full boot log, and U-Boot environment are expected.

danybd wrote: I supposed if my bootloader works with 2.6 should wirh 5.X too. Am I wrong?
Yes.
The Linux ARM booting requirements have changed: a Linux ARM 2.6.x kernel is built with a board file and is passed ATAGs, whereas a modern kernel uses a (separate) Device Tree blob.
But there is a method for the kernel to be be backwards compatible when using a bootloader that does not know how to handle the Device Tree blob.
The kernel can be built with the DT blob appended to it, so that there is just a single image file.

BTW:
Despite being a "legacy system", a new Fox Board G20 can still be purchased from Acme Systems.
The "last kernel provided by the board producer" is not based on Linux 2.6.x but rather 3.11.

Regards
danybd
Posts: 3
Joined: Tue Nov 17, 2020 8:01 pm

Re: Last supported kernel AT91SAM9G20

Mon Nov 23, 2020 9:32 pm

Thank you very much for the response. I really appreciate your help. As in my last message I did not provide information about the context, I´m going to fix it.
The bootloader I´ve been trying to use is the AcmeBoot https://github.com/tanzilli/AcmeBoot, which is a tailored version for the FOX G20 board, based on Atmel AT91Bootstrap v.3.0
My first try was to use directly the current at91bootstrap but I experimented some troubles with the Data Flash, which seems to be somehow not compatible with the last versions of AT91Bootstrap. For this reason I tried as fallback the original AcmeBoot bootloader ignoring the big difference between modern kernels and old ones (ATAGS vs Device tree).
Right now it looks to me like I have only 2 options, if I want to run an up to date kernel on my target:
- Try to modify the AcmeBoot so that can deal with a device tree
- Try to modify AT91Bootstrap so that it works with the Data Flash built on my target
Any of these tasks are going to be pretty challenging for me, as this my first time building linux from scratch.
blue_z
Location: USA
Posts: 2131
Joined: Thu Apr 19, 2007 10:15 pm

Re: Last supported kernel AT91SAM9G20

Tue Nov 24, 2020 2:44 am

danybd wrote: Thank you very much for the response. I really appreciate your help. As in my last message I did not provide information about the context, I´m going to fix it.
I don't see a boot log.

danybd wrote: Right now it looks to me like I have only 2 options, if I want to run an up to date kernel on my target:
- Try to modify the AcmeBoot so that can deal with a device tree
- Try to modify AT91Bootstrap so that it works with the Data Flash built on my target
Why are you ignoring the kernel workaround?

Regards

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