[U-Boot-Users] RAM vs. ROM version of ppcboot

[Stephan Linz]

Am Dienstag,  3. Dezember 2002 13:55 schrieb Wolfgang Denk:
> In message <02120313135706.06014 at pcj86.jena.mazet.de> you wrote:
> > I hope it's right to post questions about PPCBoot at U-Boot mailing list.
> > I'm
>
> Given the fact that PPCBoot has been laid to rest, yes.
>

Yes I know. My running project will be using PPCBoot anymore.

> > new at PPCBoot, but know about internals of ARMBoot. So I know the ROM
> > and RAM versions of ARMBoot have to differ.
>
> Ummm... you don;t need a "RAM version" at all.
>
> > Now, I plan to download PPCBoot into the RAM of a TQM850L via gdb and run
> > from there. Gdb init the target processor inclusive address decoder. Can
> > I load a ppcboot binary builded from plain tarball into the RAM or
> > schould I swap some configs in include/configs/TQM850L.h ?
>
> Why would you want to  do  this?  U-Boot  (and  PPCBoot)  is  running
> perfectly  fine  from  flash  on all TQ boards. Why would you want to
> create a "RAM version"? It makes no sense to me.
>
I'm using TQ board for studies and learn to swim. The final PPCBoot will be 
running at my own plattform which is similar to TQ. So I plan to clone the TQ 
board in PPCBoot and change something in flash.c and tqm8xx.c.

Why RAM version? Hmm, after hardware production my own target has no code at 
flash. So I could download an ppcboot into flash via debugger, but my 
VisionCLICK from Windriver doesn't know about the flash briks at my own 
target (ha, TQ boards too :-). The last chance I have is to use my MPCBDM. 
But til now I don't know abot flash access via MPCBDM. There is no further 
doc and I have no time for try'n error.

Thus I plan to use ppcboot running from ram and download / burn to flash 
itself.

But for all that: Is there any step by step manual how to use the MPCBDM 
flash facility? Where can I found HOWTOs or FAQs about PPCBoot debugging via 
gdb (MPCBDM).


Thanks and best regards,
Stephan

> As the CPU  starts  executing  code  from  the  boot  device  (CS0  =
> typically  flash)  this is the most natural mode to run PPCBoot, too.
> It was written to expect a CPU coming up from reset, so  don't  force
> it  into  any other environment without a good reason and a very good
> understanding of what you do, and why.
>
> Since you ask this question, I think you should NOT try doing this.
>
>
> Best regards,
>
> Wolfgang Denk

-- 

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Stephan Linz
Software Engineer

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