Booting linux on MPC custom Board

Booting linux on MPC custom Board

[Lokesh Kumar]

Hi,
I have a custom board with a custom bootloader. The board is based on
MPC855T, with 8MB flash and 32MB RAM.

I have to boot linux on this board. The issue I have is this - I have to use
the custom bootloader (to be able to boot older app as well). I think I have
two ways to go -

1. Custom bootloader enhanced to be able to load Linux. I do not think it is
faster approach given the time required.

2. Tell custom bootloader to load another bootloader like PPCBOOT (U-BOOT)
and then let it load Linux. Now, to go this route, I will have to run
PPCBOOT from RAM. Reading documentation of PPCBOOT, it says that it runs
from FLASH and relocates itself to RAM.
	How can run PPCBOOT from RAM directly and then tell it to load
Linux?? Any HELP would be appreciated.


Lokesh Kumar
Wireless Matrix USA Inc.
703-262-4032


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Re: Booting linux on MPC custom Board

[Wolfgang Denk]

In message <3439AB3A99ECD5409F3A52ACF814744D158D36@norcom2.norcom.net> you wrote:
>
> I have a custom board with a custom bootloader. The board is based on
> MPC855T, with 8MB flash and 32MB RAM.
>
> I have to boot linux on this board. The issue I have is this - I have to use
> the custom bootloader (to be able to boot older app as well). I think I have
> two ways to go -
>
> 1. Custom bootloader enhanced to be able to load Linux. I do not think it is
> faster approach given the time required.

Maybe, maybe not. If you don't need any  nice-to-have  things  it  is
very simple to boot Linux on any bootloader.

> 2. Tell custom bootloader to load another bootloader like PPCBOOT (U-BOOT)
> and then let it load Linux. Now, to go this route, I will have to run
> PPCBOOT from RAM. Reading documentation of PPCBOOT, it says that it runs
> from FLASH and relocates itself to RAM.
> 	How can run PPCBOOT from RAM directly and then tell it to load
> Linux?? Any HELP would be appreciated.

Such  a  question  will  receive  much  better   responses   on   the
u-boot-users mailing list. In short: configure U-Boot to be linked at
a specific RAM address, disable the RAM initialization code and other
parts  that have already been done by your bootloader, load it to the
chosen address in RAM, and start it at offset 0x100.


But there is probably a 3rd option: install U-Boot, and let  it  boot
your "older apps". U-Boot supports more than just Linux.


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
"In Christianity neither morality nor religion come into contact with
reality at any point."                          - Friedrich Nietzsche

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RE: Booting linux on MPC custom Board

[Lokesh Kumar]

Thanks a lot. I am going to follow your advice and start rolling.

Lokesh

-----Original Message-----
From: li [mailto:slowforce@21cn.com]
Sent: Monday, June 23, 2003 12:45 PM
To: Lokesh Kumar
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: Booting linux on MPC custom Board


Hi Kumar,
1. change the TEXT_BASE definition in the
   board/yourboardname/config.mk to pointer to sdram
   base
2. change the CFG_FLASH_BASE and CFG_MONITOR_BASE
   definition to that address in the
   include/config_yourboardname.h
3. comment the BR0 reset in section in
   cpu/mpc8xx/cpu_init.c
4. comment the sdram init function(initdram), just set
   the ram size manually
now, you can compile the ppcboot, and download the ppcboot.bin to the
address which the TEXT_BASE point to and make it run.
Good Luck!
Li

>
> Hi,
> I have a custom board with a custom bootloader. The board is based on
> MPC855T, with 8MB flash and 32MB RAM.
>
> I have to boot linux on this board. The issue I have is this - I have to
use
> the custom bootloader (to be able to boot older app as well). I think I
have
> two ways to go -
>
> 1. Custom bootloader enhanced to be able to load Linux. I do not think it
is
> faster approach given the time required.
>
> 2. Tell custom bootloader to load another bootloader like PPCBOOT (U-BOOT)
> and then let it load Linux. Now, to go this route, I will have to run
> PPCBOOT from RAM. Reading documentation of PPCBOOT, it says that it runs
> from FLASH and relocates itself to RAM.
> 	How can run PPCBOOT from RAM directly and then tell it to load
> Linux?? Any HELP would be appreciated.
>
>
> Lokesh Kumar
> Wireless Matrix USA Inc.
> 703-262-4032
>
>
>

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