Porting linux ppc to new platform

Porting linux ppc to new platform

[mark]

  Hello,

  I apologize if there is a FAQ for this loaded question, but I did not
immediately see one.


  I have been playing with linux for about 5 years and playing with the
kernel for about 1, but only on x86.


  Recently I have begun working with ppc and have ported vxWorks to our
platform and am now interested in porting linux.  I have gotten the RPX
lite board to boot, but then I really did not have to do anywork.

  What I'm intrested in is others who have ported linux to embedded platforms
so that I might ask them the amount of work invovled and where is a good
place to begin.  This will be on a board with no available firmware or drivers,
although I can perform enough low level configuration to bring up vxWorks.

  Is there specific memory layout required, what types of cpnfiguration is
neccessary at the hardware layer (immr, sypcr, icdct, mamr level stuff, etc.).
What do I need to do vs. what is done in the ppc kernel after it is capable
enough to load a C program.  Is there a powerpc equivalent to lilo,
or is this even needed.  Can I just jump to main.c?

  I have many more questions, but if these aqre answered by a FAQ I'll hold off until I can investigate more.

Thank you

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Re: Porting linux ppc to new platform

[Wolfgang Denk]

Dear Mark,

in message <E13GYf7-0000Lz-00@sps.la.asu.edu> you wrote:
>
>   Recently I have begun working with ppc and have ported vxWorks to our
> platform and am now interested in porting linux.  I have gotten the RPX
> lite board to boot, but then I really did not have to do anywork.

Check the Embedded PowerPC HOWTO at
http://members.xoom.com/greyhams/linux/PowerPC-Embedded-HOWTO.html

>   What I'm intrested in is others who have ported linux to embedded platforms
> so that I might ask them the amount of work invovled and where is a good
> place to begin.  This will be on a board with no available firmware or drivers,
> although I can perform enough low level configuration to bring up vxWorks.

There are several Open Source firmware projects:

* PPCBOOT - Embedded PowerPC Linux Boot Project - MPC8xx, MPC82xx
  Homepage: http://ppcboot.sourceforge.net/
  Download: ftp://ftp.denx.de/pub/ppcboot or CVS on Sourceforge

* LiMon - Linux Monitor - SBC8260
  Homepage: http://www.thinsys.com/limon.html
  Download: http://www.thinsys.com/limon-1.4.2.tar.gz

* PBOOT - PMON/2000 BootROM Monitor - 603e, 604, 604r, 740, 750
  Homepage: http://pmon.groupbsd.org/
  Download: ftp://pmon.groupbsd.org/pub/PMON/src/

>   Is there specific memory layout required, what types of cpnfiguration is

Yes. Life will be easier for you when RAM starts at 0 and IMMR is  at
0xFFF00000  (assuming  you  stay  on MPC8xx as the use of an RPX lite
indicates).

> neccessary at the hardware layer (immr, sypcr, icdct, mamr level stuff, etc.).

These things are usually done by the firmware.

> What do I need to do vs. what is done in the ppc kernel after it is capable
> enough to load a C program.  Is there a powerpc equivalent to lilo,
> or is this even needed.  Can I just jump to main.c?

Using PPCBOOT,  you  can  "jump"  to  the  entry  point  "_start"  in
arch/ppc/kernel/head.S  using the "bootm" command - but this includes
_some_ initialization (like  loading  and  uncompressing  the  kernel
image)  and  parameter  passing.  With more traditional firmware, you
will have to modify the code in the arch/ppc/mbxboot diretory to  fit
to the interfaces provided by your firmware.

>   I have many more questions, but if these aqre answered by a FAQ I'll hold off until I can investigate more.

I guess the HOWTO mentioned above will answer some, but not all.

Wolfgang

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
There's no sense in being precise  when  you  don't  even  know  what
you're talking about.                             -- John von Neumann

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