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[ts-7000] Re: Only 32M detected by RedBoot

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Subject: [ts-7000] Re: Only 32M detected by RedBoot
From: "charliem_1216" <>
Date: Wed, 03 Jan 2007 03:13:13 -0000
--- In  "hudson_nh" <> wrote:
>
> --- In  "charliem_1216" <charliem_1216@> wrote:
> >
> ....
> >
> > 
> > Just to clarify, I can use 32M fine, but only if I add the first (4)
> > banks of memory on the command line.  If I add any one of the higher
> > banks (starting at 0xe...) then I get the hard hang.
> > 
> > I've about exhausted my debugging skills, and I'll be grateful for any
> > 
> 
> I am seeing the same thing on my TS-7260.  I have tried various
> versions of redboot including one I built myself with the same
> results.  Now that it appears redboot is completely ruled out as the
> culprit I plan on digging through the kernel code some more to try to
> get to the bottom of this.
> 
> Have you dug any deeper since you posted this?
> 
> - Doug

Hi Doug --

Yes, I tried.  Lennert Buytenhek knew the problem right away, and gave
me some insight on the linux-cirrus ML [1].

To summarize, in Linux 2.6, the ep93xx memory subsystem expects all of
the RAM to be mapped within a 1G physical address range.  I haven't
looked into the 7260, but the 7250 doesn't doesn't do this when there
are two memory chips.  It is fixable, but not by mortals like me, and
there is no "quick hack" to make it work in the meantime.  (More
details are in the linux-cirrus ML archive.)

The good news is that it sounds like Lennert will take a look at
fixing it properly, at some point, don't know when.

As far as RedBoot, I was confused by that too.  AFAIUI, redboot only
maps the 32M, perhaps because that's all it needs, but it does pass
the right ATAGs to the kernel.

So for now, I'll keep using 32M, and keep passing the four required
mem= options on the command line.  Hopefully in the not too distant
future we'll be able to use a 2.6 kernel out of the box (most bits are
there and work great already!)

regards, ....... Charlie

[1] http://www.freelists.org/archives/linux-cirrus/12-2006/msg00029.html

PS -- When I wanted to move to a 2.6 kernel, I found the info I needed
by digging through ML archives, forums, etc.  Any suggestions for the
best way to centralize this knowledge to make it easier for others to
find?  (wiki anyone?).



 
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