initrd not loaded with > 4 GB and PAE kernel

[Diego Santa Cruz]

Hello,

I have installed the FC6 kernel 2.6.18-1.2849.fc6PAE on a machine with 4
GB of memory (of which the upper 2 GB are mapped by the BIOS above the 4
GB barrier).

The kernel is not booting since it does not find the initrd and thus
panics (cannot find init).

Passing the mem=4096M option to the kernel solves the problem, but
limits the actual memory to 2 GB only.

The BIOS-provided physical RAM map is:
 BIOS-e820: 0000000000000000 - 000000000009ec00 (usable)
 BIOS-e820: 000000000009ec00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000e4000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000007ffa0000 (usable)
 BIOS-e820: 000000007ffa0000 - 000000007ffae000 (ACPI data)
 BIOS-e820: 000000007ffae000 - 000000007ffe0000 (ACPI NVS)
 BIOS-e820: 000000007ffe0000 - 0000000080000000 (reserved)
 BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
 BIOS-e820: 00000000ffb00000 - 0000000100000000 (reserved)
 BIOS-e820: 0000000100000000 - 0000000180000000 (usable)

The grub config is:

title Fedora Core (2.6.18-1.2849.fc6PAE)
        root (hd0,0)
        kernel /boot/vmlinuz-2.6.18-1.2849.fc6PAE ro root=/dev/md0 rhgb
quiet
        initrd /boot/initrd-2.6.18-1.2849.fc6PAE.img

Grub version is grub-0.97-13.

I also reported this on bugzilla at
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=218470

Any ideas on what could be wrong?

The MB is an ASUS P5B deluxe, with an Intel 965 chipset.

Thanks,

Diego