[U-Boot] U-boot and linux command line parameters

Dear All,

I use linux kernel 2.6.23 and u-boot 1.2.0 (on ppc405 virtex-4 ) for some time. All works fine when the kernel together with initramfs is smaller than 8MB. If it is bigger than the kernel does not boot properly.

First of all I would like to know how the address for the linux command line parameters is "transferred" from u-boot to linux for ppc405 (virtex4 chip)? (via some registers or is it a fixed address in the memory ie. 8MB?) Does somebody know what should be changed, in the kernel, in order to move this limitation from 8MB to let say 12MB? I would be grateful for any hint.

Thanks in advance. M.