440GX MMU problem

[Barbier, Renaud (GE Infrastructure)]

I am using linux 2.4.26 on a 440GX with 512MB of SDRAM.
>From U-boot I can see the whole memory.
If I boot Linux, unless I set the boot parameter mem=256M (or less).
it will not boot. Linux does not seem to go further than the MMU_setup.

Any idea why it cannot use 512MB?

thanks.