[LinuxBIOS] 440BX progress.

Segher Boessenkool segher at kernel.crashing.org
Sun Nov 26 23:18:20 CET 2006

> Hint: Try testing the lower memory:
>   ram_check(0x10000000, 0x2000000);
>   is going for 256-512 Megs.

Ah, there's the (or a) problem.  There's a zero missing.
No memory was tested at all.

> The LinuxBIOS image is copied to _RAMBASE which normally defaults to
> 0x4000 (@16k). So you might have 2 dimms a 256M and while the upper one
> works, the lower one doesnt.


> In the end the ram_check() function does not reliably test your memory.
> It will not detect whether your memory works, but it will detect 
> whether
> it fails ;-)

And not always, either.

> Also note: the order in which your registers are set may play a role.
> For example there might be a register with a DRAM_ENABLE bit which must
> be set last, after all other DRAM related bits are set, or the values
> set later on might be ignored.

Yes.  And you often have to wait for certain bits to flip
before you write other bits, etc.


More information about the coreboot mailing list