iPXE as a chain-load target

[thecoda]

So the plan is:

1 - Start GRUB2 over PXE as my initial booloader (to give me the whizzy graphics), using a script-generated config file based on a folder of ISOs

2 - When an entry is selected, chain-load iPXE (for the sanboot capability)

3 - Chain-load (via sanboot or memdisk) the required ISO

All good in theory, but the documentation doesn't suggest any way to pass parameters into iPXE other than via DHCP.

My current thinking is to roll a custom TFTP server and undionly hard-wired to run a script from that server. I can then embed the ISO name or index into the chain-load path (e.g. tftp://myserver/path/undionly?iso=hiren.iso) and reuse it when the script is requested (e.g. tftp://mysever/path/dynscript.ipxe)

The TFTP server would then return undionly and remember the iso param from this request (keyed to the asking IP or MAC). When asked for the hard-coded script from the same IP it would use the retained param to return a script that proceeded directly into a sanboot of the requested ISO.

This is a bit easier than my original idea of implementing an http module for GRUB2, but it's still a fairly involved solution!

So my question: Is there an easier way to pass parameters directly into iPXE when chain-loading it from GRUB2? I could then use an off-the-shelf TFTP implementation and my server-side logic would be restricted to generating the grub config file.