[U-Boot-Users] Re: Re: really really tiny code

Nishant Galange nishant.subs at myrealbox.com
Wed Jan 26 13:59:52 CET 2005

Sorry about the off-topic email. I sincerely felt that the people 
on this mailing list are the only ones who can help me.

About the problem itself:
Yes, I am a little comfortable with the u-boot source code now, and 
I planned on using most of the code in cpu/mpc8260/start.S for making this 
'micro monitor' 

I definitely plan to make it available under the GPL, as I feel it 
will be a really good test tool for people bringing up their new hardware 
for the first time. They can use the processor to test crucial parts of 
the system, and use LEDs to report status. From my (limited) experience 
in board bring-up, everything right from the power supply to bad buffers, 
JTAG connections to bus noise are suspect when the board dosen't work. 
Atleast this tiny code will help clear up doubts from the processor's 
point of view. Developers will have one definite ally on the board who keeps 
sending status reports no matter what else is failing.

The only help I need is with gcc, or ppc_82xx-gcc, to be precise. 
I have no idea how to give it a single .S or .asm file and tell it to create a .bin. 
Makefiles? I only know how to use readymade ones, not to how to create one.

You said I will also need a .lds, and I don't know how to tell gcc to use that either.

Can anyone please send the complete process of compiling such a source 
(only 1 or two source files) along with the .lds and creating a .bin?


PS. Sorry again if its still off-topic. But I feel it can be a good addition 
to u-boot as a separate tool. This will also be independent of the board, 
and most people will simply have to change the 
addresses of the LEDs to get it working for 
their board.

-----Original Message-----
From: wd at denx.de [mailto:wd at denx.de]
Sent: Wednesday, January 26, 2005 3:05 PM
To: Nishant Galange
Cc: u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] really really tiny code 

In message <1106684792.3804b95cnishant.subs at myrealbox.com> you wrote:
> I want to write a really tiny program - just init core, MMU and stop.
> Preferably, (if possible) I would like to start out with a blank file, 
> type in the code, and give the compile command at the good old command prom=
> pt. 
> Is it possible? If yes, can anyone please tell me the command? 

Yes, it is poossible. You will need more than one command,  at  least
"vi" and "ppc_82xx-gcc".

> Would any other files (.lds, etc) be necessary? What else will be required?

Yes, you will most probably need a linker script.

One of the most important requirements is an  in-depth  understanding
of your hardware environment and how to write software for it.

> I need a micro development environment like this from where I can do all 
> my work out of the cosy little (really limited, I know) DPRAM, and try 
> out some experiments with the processor's registers and config.
> I might even be adventurous and try initializing the ports and 
> glowing some LEDs :-)
> What do I do? How do I proceed? Please help.

U-Boot includes all the init stuff you will probably  re-0invent,  so
feel  free  to  copy  and  re-use  this  code  (and make your program
available under GPL), but please understand that you are on your  own
with such a project.

Sorry, but this is off topic here.

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
A year spent in artificial intelligence is enough to make one believe
in God.

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