Hi Jürgen, 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. Regards, Carl-Daniel -- http://www.hailfinger.org/ -- coreboot mailing list [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
