HMNHD - CE - Understanding Boot Sequence

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hellpoet
Posts: 20
Joined: Wed Sep 24, 2014 10:27 am

HMNHD - CE - Understanding Boot Sequence

Post by hellpoet » Fri Jan 30, 2015 2:45 pm

Hello, I successfully installed the wheezy 3.12 following the guides in these forums. What now I am interested to do is understanding the boot part creation (first 32mb) How that part works and Where i can start compiling them for example to be able to boot a newer kernel.
The most lately updated git repository on the subject are:

https://github.com/kref/u-boot-oxnas

https://github.com/kref/linux-oxnas

But i don't know where to start. Basically i want to compile a new u-boot and install a 3.16 kernel.
Any help on where i can start is appreciated.

Thanks

Mijzelf
Posts: 6194
Joined: Mon Jun 16, 2008 10:45 am

Re: HMNHD - CE - Understanding Boot Sequence

Post by Mijzelf » Fri Jan 30, 2015 4:20 pm

I'm not experienced in this, here are my 2 cents:

According to the Wiki the Stage-1 bootloader expects u-boot starting at sector 154. The rest is up to you. If you let u-boot load uImage as file from a partition (the way I would do it) that is all. If you don't, you will have to define yourself where you put uImage (and maybe uInitrd).

hellpoet
Posts: 20
Joined: Wed Sep 24, 2014 10:27 am

Re: HMNHD - CE - Understanding Boot Sequence

Post by hellpoet » Sun Feb 01, 2015 4:32 pm

I understand, the thing that is not clear to me is:
If i leave untouched the first 32MB with your files, would i able to boot other rootfs ported for OXNAS.

I think i will play with this, and come back with the results :)

Mijzelf
Posts: 6194
Joined: Mon Jun 16, 2008 10:45 am

Re: HMNHD - CE - Understanding Boot Sequence

Post by Mijzelf » Wed Feb 04, 2015 8:37 am

If i leave untouched the first 32MB with your files, would i able to boot other rootfs ported for OXNAS.
No. Yes. Using this '32MB', the box will run the kernel and initrd which are inside it. That initrd contains some complicated scripts to assemble and mount the volumes.

To run your own rootfs (which hasn't to be ported, BTW, Debian for armel will run fine), you'll have to either exchange the initrd, or change the u-boot environment (I think you'll need serial for that) to leave the initrd, and push a 'normal' rootfs instead using the command line, or exchange the kernel by one which ignores the commandline, and uses it's own.

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