No subject

"The instruction side and data side can share a 64MB address space, or each
can have its own 64MB address space. The address spaces are fully
relocatable on 64MB boundaries within the 4GB address space of the
PPC405GPr, but the programmer must assign OCM address space to avoid
conflicts with other assigned addresses."

My address map shows space from 0000 0000 to E7FF FFFF as 'General Use.'
This space is where most relocatable devices can be placed.

The DCU (Data Cache Unit) is controllable; but not directly addressable.

So if I read correctly, the OCM for the 405GP is not a function of how the
board is "wired", but how I set it up programmatically.  However it seems
that you are indicating that it depends on the design of my board.  Can
you please help provide clarification.

Thanks

Jerry

-----Original Message-----
From: wd at denx.de [mailto:wd at denx.de]
Sent: Sunday, January 05, 2003 3:46 PM
To: jwalden at digitalatlantic.com
Cc: u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] PPC405GP - uboot - can't get past stackloop


In message <EGEGIJHKDKJGAJMGIDPNMEAHCEAA.jwalden at digitalatlantic.com> you
wrote:
> Yes - you are absolutly correct.

Been there myself often enough before ;-)

> Somewhere after about 1000 iterations of placing 0xdeaddead into what is
> supposed to be the temporary stack frame, I get a machine exception.
>
> So - now I know my memory is not configured correctly.  My hardware guy is

Probably not your _memory_.

> not
> here, however I see that he has defined 64MB starting at 0x70000000.

Ignore that. RAM should always start at 0x0000.

> However if
> I change the value in my config file (CFG_INIT_RAM_ADDR) from 0x4000000 to
> 0x7000000

Be careful! The initial memory is NOT in  RAM!!!  It  used  the  data
cache  or OCM - don't know the design of your board. If in doubt, use
the data cache.

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
This all sounds complicated, but it mostly does excatly what you  ex-
pect. It's just difficult for us to explain what you expect...
                       - L. Wall & R. L. Schwartz, _Programming Perl_