I have now got Slackware 14.0 booting using grub.efi. The advantage of this for me over elilo or my previous setup ( which was grub installed to the MBR of a second hard disk ) is that by default it brings up a menu and it will boot Windows. So far I have the boot disk on USB but the next stage when I am brave enough is to put this on by hard drive
What I did was as follows:
Follow the instructions here
to create the usb stick. That is partition the USB drive with a GPT scheme having a FAT32 partition type code EF00
Add an ./EFI/BOOT/ structure to the drive.
Install grub2 using the slackbuild but modifying it by adding
I then followed some of the instructions here
Mount the usb at /boot/efi
# mount /dev/sdc1 -t vfat /boot/efi
# modprobe dm-mod
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --recheck --debug
# mkdir -p /boot/grub/locale
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
Configure grub.cfg with
grub-mkconfig -o /boot/grub/grub.cfg
This process created a file on the USB stick
/EFI/arch_grub/grubx64.efi. I found that my UEFI system was not seeing that so I copied it to /EFI/BOOT/bootx64.efi
I now was able to boot using UEFI from the USB via a grub menu. Grub.cfg needed manual editing to get the generic kernel as default and to add Windows.
This needs a little polishing up but I hope that people find it useful.