Geode GX1 and IRQ tables

Ian Smith ian at
Tue Mar 1 22:23:00 CET 2005


At 04:02 02/03/2005, ramesh bios wrote:
>1. Shadow RAM
>I guess I would need to find a way to tell the
>northbridge to enable shadow RAM for some range around
>f0000. I looked through the CS5530A datasheet and see
>shadow registers but no mention of shadowing RAM. Nor
>in the GX1 datasheet either. I'm looking for some
>register in either the GX1 or the CS5530A that would
>enable this. I am looking for some register that would
>enable me to remap the C0000-F0000 address range to
>somewhere in sdram. Is that the right thing to be
>looking for?

I think you may need to look at your settings for the BC_XMAP_2 and 
BC_XMAP_3 registers on the GX1 - these control read and write access to the 
BIOS shadow ram regions.

>2. Uncompressed payload
>I'm not sure I understand what this means. Right now,
>my payload is filo. In the build, I see:
>dd conv=sync bs=196608 if=/bios/filo-0.4.2/filo.elf
>cat payload.block > romimage
>Oh, I guess you must mean this stuff:
>objcopy -O binary linuxbios_c linuxbios_payload.bin
>./nrv2b e linuxbios_payload.bin
>So I guess there is some kind of compression going on

Not sure if you're using Linuxbios V1 or V2 but in V1 there is an option in 
your build config file to turn off compression - you probably need 
something like:


If it's V2 then no doubt there is an equivalent there too.

>Which method would be the right thing to do? I'll look
>at the shadow ram thing first then.

Nope this helps


>--- "Ronald G. Minnich" <rminnich at> wrote:
> >
> >
> > On Tue, 1 Mar 2005, ramesh bios wrote:
> >
> > > Strike that. The issue is somewhere with
> > > copy_pirq_routing_table. IE: why does the copy to
> > > f0000 fail. I had assumed that the 500 address was
> > an
> > > alternate location that the table was copied to.
> > So
> > > now, I'm looking at that f000 failure.
> >
> >
> > the copy to f0000 fails because shadow ram is not
> > set up.
> >
> > You can fix this one of two ways. One is to figure
> > out how to enable
> > shadow ram. The second is to make the payload
> > uncompressed. The copy will
> > still fail but linux will find the PIRQ table
> > anyway.
> >
> > ron
> > _______________________________________________
> > Linuxbios mailing list
> > Linuxbios at
> >
> >
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