grub-probe failed on /dev/ram0

[Emmanuel Jeanvoine]

Hi all,

I have some trouble about grub-legacy and its installation (I use a
Debian Lenny). I'll try to present my problem:
1/ I boot a computer with PXE and Linux kernel and I use the initrd as a
root partition (as a consequence, / is on a ramdisk on /dev/ram0)
2/ my computer has a hdd (/dev/hda) and I'd like to install grub
on /dev/hda3
3/ so I mount /dev/hda3 on /mnt and I use grub-install with the
following cmd line: grub-install /dev/hda3 --root-directory=/mnt
4/ thus, I can see dans the grub images (stage1.5, stage2 ...) are
well copied in /mnt/boot/grub
5/ at this stage, no bootloader is installer on /dev/hda3 (I don't
really know why), so I perform another grub-install without the
root-directory parameter this time.

At the last step I get the following error "grub-probe: error: Cannot
find a GRUB drive for /dev/ram0.  Check your device.map."

My device.map only contains: (hd0)      /dev/hda

If I don't boot the computer with the ramdisk via PXE, but directly
using the mbr and /dev/hda1, all these steps can be performed correctly.

So I have two questions:
- Do you have any idea for the problem about grub-probe and /dev/ram0 ?
- Do you know why the step 5 is required to really install the
bootloader on /dev/hda3 ?

Thanks

Emmanuel.