correct grub2 menuentry stanza for chainloading xen.efi?

[lyndat3]

I'm booting Xen 4.5 on UEFI with GRUB2.

For now, that requires chainloading

        http://wiki.xenproject.org/wiki/Xen_EFI

I'm trying to get the menuentry root correct, and disk-position-independent.

My efi partition partition is mounted at '/boot/efi'

        grub2-probe --target=device /boot/efi
                /dev/sdg2
        mount | grep efi | grep ^/dev
                /dev/sdg2 on /boot/efi type vfat

that target dir/file on the efi partition I need to load is

        ls -al /boot/efi/EFI/XEN/xen.efi
                -rwxrwxr-x 1 root root 2.1M Mar 27 21:20 
/boot/efi/EFI/XEN/xen.efi*

Dropping to grub2 prompt on reboot, autocomplete finds only the lowercased-

        set root=(hd6,gpt2)/efi/xen/xen.efi

but does NOT find

        set root=(hd6,gpt2)/EFI/...

given the REAL path of

        .../EFI/XEN/...

but the grub2-found path of

        .../efi/xen/...

Which path should be used in a menuentry stanza?  lowercased, or not?

Next, (hd6,gpt2) this is disk-position-dependent

To get/use a permanent/immutable drive-specific root in grub2, is use of 
'device.map' (as in grub-legacy) still the right approach?

It seems that in default/generated grub.cfg, *uuid-specified roots are used

For this system

        blkid /dev/sdg2
                /dev/sdg2: UUID="94C3-29F3" TYPE="vfat" PARTLABEL="EFI Sys 
Part" PARTUUID="8456ded4-2c33-53f2-8465-5c87757d9c0a" 
        find /dev/disk | egrep "94C3-29F3|8456ded4|EFI"
                /dev/disk/by-uuid/94C3-29F3
                /dev/disk/by-partuuid/8456ded4-2c33-53f2-8465-5c87757d9c0a
                /dev/disk/by-partlabel/EFI\x20Sys\x20Part

Given the above, how should the menuentry

        menuentry 'Xen' {
                insmod part_gpt gpt
                insmod diskfilter mdraid1x
                insmod ext2
                insmod search_fs_uuid
                insmod chain
                set root=(hd6,gpt2)
                chainloader /EFI/XEN/xen.efi
        }

be edited so the lines

        set root=
        chainloader

correctly

        -- use a 'fixed', drive-specific UUID
        -- use the right case for grub2 chainloading

?

LT