Making linux boot on a powerpc board. What is needed?

dodo76 · 11-11-2010, 08:59 AM

A BIG question.

I'll try to make it smaller.
I have a board with a powerpc processor and some peripherals (PCIe, Compact Flash, PHY, DDR3 etc.).
I'm using U-boot from which LAWs and TLBs are set. Also I have a DTB from a similar board.
Booting linux from here and it just dies. No printouts what so ever.

The question is: What are the bare minimum areas that are needed to be changed in the kernel for getting a login prompt?

I was actually hoping that I would be able to boot linux with a RAM disk without changing the kernel. I thought the OF interface would take care of most hardware dependent issues. Obviously I'm wrong.

Thanks
Robert

nini09 · 11-11-2010, 03:12 PM

You can use busybox to get a login prompt if kernel is up.

dodo76 · 11-12-2010, 05:57 AM

Quote:

Originally Posted by nini09

You can use busybox to get a login prompt if kernel is up.

Thanks for answering but it seems my question was not clear. My kernel is not up. That is the whole point. I meant that I wanted to know what, in general terms, need to be changed in the kernel to make it come up all the way to the login prompt. (Naming the login prompt was just a way to say: "Booting all the way").

BR
Robert

nini09 · 11-12-2010, 02:32 PM

1)Build your board kernel.
2)Make root file system.
3)Check console output if kernel boot is failure.

pavius · 11-13-2010, 05:53 AM

You're not wrong, the DTB should be able to take care of the hardware specifics. Having just booted linux on a 875, I can tell you that all of my issues booting linux were related to what u-boot was passing to linux, specifically the ftd. There was absolutely nothing i needed to change in the linux sources to get the board up.

If you do not have a JTAG device, look at what bootm does. I was missing two directives in my /include/configs/ header:

#define CONFIG_OF_LIBFDT
#define CONFIG_OF_BOARD_SETUP

Without these, u-boot does not pass the ftd blob to linux and what are you describing (after bootm the kernel gets stuck) will happen. You must make sure that you pass the dtb on to u-boot by some means and pass this offset to linux.

If your DTB does not hardcode the frequency values (which is correct), make sure to call ft_cpu_setup() in u-boot to populate these values dynamically prior to passing the blob to linux. Do this by implementing ft_board_setup in your board file.