[coreboot] [PATCH] Support for the ASI MB-5BLGP (Neoware Eon 4000s)

[Juergen Beisert]

Hi Carl-Daniel,

On Montag, 14. Juli 2008, Carl-Daniel Hailfinger wrote:
> On 14.07.2008 10:21, Juergen Beisert wrote:
> > Hi Carl-Daniel,
> >
> > On Montag, 14. Juli 2008, Carl-Daniel Hailfinger wrote:
> >> thanks a lot for the code.
> >>
> >> On 13.07.2008 22:50, Juergen Beisert wrote:
> >>> On Sonntag, 13. Juli 2008, Carl-Daniel Hailfinger wrote:
> >>>> [CAR for GX1]
> >>>
> >>> Its not adapted to v2 nor v3. Its only an example, how to do it for
> >>> CPUs with these special cache test registers (like older i486 and the
> >>> Geode GX1).
> >>
> >> You say "older i486". Does that mean newer i486 have different
> >> registers?
> >
> > No, that's not what I mean. All i486 are "old", aren't they? ;-) My
> > amd486 datasheet tells me, this CPU has such registers. I believe the old
> > Intel i486s also have such registers (but I'm not sure).
>
> Thanks for clarifying.
>
> >>> After running this program, you have (a very fast) RAM at physical
> >>> address __car_data_dst up to (__car_data_dst + __car_size). These two
> >>> symbols are generated by my linker script. I'm using this code in my
> >>> current u-boot-v2 development for ia32.
> >>>
> >>> Note: This code must run with *disabled* cache and this piece of RAM
> >>> only exists and is useable, _until_you_enable_the_cache_!
> >>> Note also: You should locate this CAR area in the regular SDRAM area,
> >>> because when you enable the cache (after SDRAM controller
> >>> initialisation), the cache unit will flush its content to the SDRAM. It
> >>> will fail badly if at the same physical address is no real memory to
> >>> write/flush to.
> >>
> >> Hm. I thought a self-copy followed by a WBINVD was required to transfer
> >> the cache contents to the SDRAM.
> >
> > But also the WBINVD will fail, if at the physical mapping address is no
> > valid device (like SDRAM or PCI...). In this case you must use the INVD
> > instruction instead. But I believe you know what you are doing ;-)
>
> Yes, my question was mostly about the lack of WBINVD in your code.
> Having a CAR area not backed by SDRAM would be "interesting", not to say
> stupid in our case.
>
> I think I have figured out where to merge your code into the existing
> Geode LX CAR code.

The Geode LX lacks these cache test registers! Only the GX1 supports them.

Juergen