GRUB2 PXE chainloading and EFI handles

[kitzman]

Dear all,

I'm here to ask for some help - I'm not an EFI expert so brace 
yourselves.

I have the following situation: I PXE boot EFI GRUB2, which has menu 
entries for some operating systems.
One of the operating systems requires chainloading its bootloader. That 
bootloader checks if it should/can
boot from PXE, ISO, or local disk (in this order). The way the PXE check 
is done, is that it loads EFI
handles related to PXE, and, if it can, it initiates a PXE boot (which 
uses other EFI handles, for networking).

My problem is that: once GRUB2 chainloads, and the second bootloader is 
running, some EFI handles
are not there. So it falls back to local disk boot.

Is there a way to tell GRUB to leave the handles there as if it's a 
regular PXE boot? Maybe it's not GRUB2
deciding if those handles should be there anymore? I don't know.

Kind regards,
kitzman