BeagleBoard rev C3?

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BeagleBoard rev C3?

Postby WizardStan » Mon Jul 25, 2016 11:57 am

Hi,
is the C3 supported at all?
The u-boot in http://os.archlinuxarm.org/os/ArchLinux ... est.tar.gz doesn't work on it (most likely because of changes between C4 and C5) so I had to build from source with the required patches.
The default bootcmd doesn't play well so I updated it as so:
setenv bootargs "console=${console} vram=${vram} rootfstype=ext4 root=/dev/mmcblk0p2 rootwait rw"
setenv bootcmd 'run findfdt; load mmc 0:1 ${fdtaddr} /dtbs/${fdtfile}; load mmc 0:1 ${loadaddr} /zImage; bootz ${loadaddr} - ${fdtaddr}'

But all I get is
reading /dtbs/omap3-beagle.dtb
107229 bytes read in 24 ms (4.3 MiB/s)
reading /zImage
5085296 bytes read in 379 ms (12.8 MiB/s)
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Loading Device Tree to 8ffe2000, end 8ffff2dc ... OK

Starting kernel ...

And then nothing. Unless the console has changed? This is what I've got, can anyone confirm that theirs is the same?
console=ttyO2,115200n8
I've also tried fatload since it is loading the dtb and zImage off my FAT16 partition but it's the same.
Any way to get this to work?
Thank you.
WizardStan
 
Posts: 2
Joined: Mon Jul 25, 2016 11:44 am

Re: BeagleBoard rev C3?

Postby summers » Tue Jul 26, 2016 9:07 am

Sounds odd. I have an A5 and both arch uboot, and arch itself, work fine.

What the below seems to say is that the kernel isn't starting at all. Thats strange, as I though all beagle boards had compatible CPUs, e.g. ti sitara. This should be enough to at least get something in the kernel turning. Now its possible that later beagleboards have the various pins wired up in in a different way (possible, but unexpected) - this would mean you would need a different device tree.

When you say you have redone the uboot, is this just on the external SD, or on the flash on the board? As far as I could work out it always boots the uboot from the flash, then just if right buttons are pressed takes the kernel and root from the SD. You should be able to tell from the early uboot messages. That said though this doesn't look like your problem.

So I think check carefully you are using the right kernel and device tree. Other than that not sure there is much I can say that would help ...

EditeEditEdit: Oops - I'm talking about the beaglebone black, of course the beagle board doesn't have flash IIRC. And a different cpu (omap) ...
summers
 
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Re: BeagleBoard rev C3?

Postby WizardStan » Wed Jul 27, 2016 2:59 am

Thanks for trying. Yeah, I'm talking about the 9 year old original OMAP3 BeagleBoard here, not the BeagleBone. I don't hold out much hope of compatibility, my biggest beef is that all the old documentation that I used to use has been "modernized" for the -xM and BeagleBones, so I'm digging through archive.org trying to find what I need mostly.
Anywho, Rev C5 made a change to the RAM that is incompatible with C4 and earlier, change which is in mainline for u-boot so I had to compile it from source with patches, and for now am forcing it to boot directly off SD card. As soon as I've confirmed everything is working as it should I'll flash it, but so far no go. I suspect the change with C5 also necessitated a change in the kernel but I can't figure out what that was or if any patches exist to undo that change, so I can't seem to get any kernel to work, unfortunately.
I'm working my way backwards, jumping a few versions, building, testing. With 3.2 I've gotten past "starting kernel" up to "booting the kernel" but that's where it freezes now. I've got a 3.0 kernel from my previous Angstrom build that I know works and if all else fails I'll use that, but I feel like a tool using a kernel that hasn't been updated in literally 5 years. I may need to seek professional kernel dev help, I'm in way over my head and am probably getting the config wrong or something simple.
So yeah, if anyone has any experience with compiling kernels for ye old BeagleBoard (not -xM, not BeagleBone) I'd appreciate any help that can be offered.
Thanks!

edit: Oh. My. Glob.
So at some point in time, somehow I got a uEnv.txt with console=tty0. I don't know where that came from. It was overwriting the correct values saved in my environment at boot. Of course I wasn't seeing any output, the old BeagleBoard needed console=ttyO2. With the 3.2 kernel I built I can now actually get somewhere. It hangs trying to mount the root partition for some reason (very strange considering /boot is on the root partition but whatever) but it's a step towards me not being completely incompetent!
WizardStan
 
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Joined: Mon Jul 25, 2016 11:44 am

Re: BeagleBoard rev C3?

Postby summers » Thu Jul 28, 2016 4:38 pm

Yes having boot messages makes it easier.

Hopefully you can scan back through the boot, to see what the root partition was detected as, and that will tell you what to set root to ....

looks like there is a beagle board device tree: http://lxr.free-electrons.com/source/arch/arm/boot/dts/omap3-beagle.dts, so hope you can move to a modern kernel.

Guess though if the memory changed, then you may need to tweak the device tree for the right beagleboard generation, e.g. set up the memory mapping and length correctly. Still if you can boot on 3.2 you should be able to find the right parameters ....

[Oh yes, uboot finds /boot when in uboot - and thats different from the kernel finding root ...]
summers
 
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