Can GRUB2 request netboot config based on client MAC or IP?

[Andrew Davidoff]

Hi,

I am playing with GRUB2 + UEFI + PXE. I'm coming from the pxelinux
world, where clients try to pull down their netboot configuration by
first looking for a file named in part by their MAC address, with
colons replaced by dashes.

I have built GRUB2 from bazaar and though I have played with it a good
deal, it doesn't appear to me that I have the ability via grub-mkimage
to introduce this behavior. The bootloader always looks for
"grub.cfg", even when the root is set to (pxe).

My first question is, is there a way to make GRUB2 try to first
request a config file based on MAC address or HEX IP, similar to
pxelinux and elilo (respectively)?

If the answer to my first question is "no", then I have a follow up:
Does the GRUB2 scripting language support something similar to "sed"?
If so this would allow me to write a simple grub.cfg that translates
colons in $net_default_mac to dashes, which would allow me to go pick
up client-specific config without having to change the names of the
files on disk. I don't see anything that looks "sedish" in
grub-core/commands or in the online documentation. The goal here is to
move to GRUB2 for UEFI PXE without having to change existing MAC based
config filenames.

Thanks.
Andy