[U-Boot-Users] PPC Discontiguous Memory Space

[Jeffery Bahr]

Danke, Wolfgang.  They do, however, pay the bills, and I'd like to have more
support for my argument.  

It *looks* like it will be some work in U-Boot (changing the bd_table) and
the kernel init routines to support discontiguous memory.  Am I right?

The second problem is that the bottom 2GB of memory would be in the 4GB-6GB
real space.  We only have 32-bit PCI, but the client is convinced that ATMU
registers would solve the mapping problem.  That's not the way I read it ...
I think every driver would have to look at the ATMU register to figure out
the reverse-mapping.

A million thanks for your quick response.  We've done 40 or 50 product board
bringups with RedBoot, CFE, and commercial BIOSes.  We really like U-Boot
and hope to use it again on future PPC and ARM projects.

Regards,
J

 

-----Original Message-----
From: wd at denx.de [mailto:wd at denx.de] 
Sent: Friday, September 15, 2006 4:52 PM
To: jbahr
Cc: u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] PPC Discontiguous Memory Space

In message <6331980.post at talk.nabble.com> you wrote:
> 
> We have a client building a PPC8548-based product who insists that we 
> allocate DRAM real address space in two large chunks at 0-2GB and 
> 4-6GB in the 36-bit address space.  It doesn't look like U-Boot's 
> bd_info structure allows for that, and it doesn't look like the Linux 
> init routines (which accesses the passed table) knows how to handle 
> discontiguous memory either (as opposed to X86 Linux, which can accept an
E820 table).

The memory map is just a matter of  software  definiton.  Ignore  the silly
request and map the RAM contiguously.

> Any comments would be VERY appreciated.

Stop people fromn doing stupid things.

Best regards,

Wolfgang Denk

--
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Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de "He
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