Chainload grub2 to grub-legacy on ahci / efi.

[Stéphan Gorget]

Hello,

I tried to chainload grub-legacy from grub2 using efi. I have the
following setup

(ahci0,gpt1) - vfat - just the efi file at that place :
/efi/redhat/grub.efi  (/boot/efi)
(ahci0,gpt2) - ext* - kernel and grub
        (/boot)
(ahci0,gpt3) - ext* - Linux FS
        (/)

I noticed that none of the device is detected as efidisk and they all
have the device id GRUB_DISK_DEVICE_ATA_ID, furthermore when I put
debug=all I can clearly see that it does not use the efidisk code
path.

I define root and prefix and try to chainload the grub.efi. However
whatever I do it end up saying "Not a valid root device". BTW
chainloading on the same setup but on BIOS works just fine, even
though I know it's a different story.

I also know I can just start the kernel from there and it works but I
would rather chainload. I can also just bail out and leave the boot
order fallback to disk, but I would like to avoid that also.
To put into context the grub2-git-version I am testing from is loaded
via network on an ipv6-only network and I want to use grub2 to replace
any pxe/ipxe/gpxe in order to simplify the decision making to just
boot local or start an imaging process.

I am pretty new to Grub and low level debugging, so maybe I am missing
something obvious or I am just trying to do something that it is not
designed for. Any help would be appreciated.

Stéphan