Problems PXE booting a UEFI debian-installer

[Andy Smith <andy@strugglers.net>]

Hi,

I'm new to machines that absolutely require EFI booting. I have a
machine that only has NVMe devices, and I understand it needs to be
installed in EFI mode to boot.

I'm trying to install by PXE. I've done this hundreds of times with
a legacy BIOS, but it's not working for me in EFI mode and I feel
like the problem is with my tftp setup or the netboot files within.

Can anyone see what I'm doing wrong here?

I've prepped my netboot server as covered here:

    https://wiki.debian.org/PXEBootInstall

Specifically where it mentions EFI I've made the changes it
suggests:

    If you are booting with UEFI, you should link grub and
    grubx64.efi into the root of your tftp directory:

    # cd /srv/tftp
    # ln -s debian-installer/amd64/grubx64.efi .
    # ln -s debian-installer/amd64/grub .

    You may also have to edit grub/grub.cfg in order to set your
    serial console, if needed (I replaced the section about the
    graphical terminal)

For that bit I just shoved:

serial --speed=115200 --unit=1 --word=8 --parity=no --stop=1
terminal_input console serial
terminal_output console serial

into the grub/grub.cfg file just after the section at the top about
setting gfxmode.

Also each of the "linux" lines in the menuentry sections I changed
them from:

    linux    /debian-installer/amd64/linux vga=788 --- quiet

to:

    linux    /debian-installer/amd64/linux --- console=ttyS1,115200n8r console=tty1

because I am doing this on a serial console.

The full content of this grub/grub.cfg file is available here:

    https://paste.debian.net/1173533/

When I trigger a PXE boot by telling the machine to give me a boot
menu, then selecting its eth0, I see it get an address from DHCP and
my tftpd logs show it request the correct files:

Nov 20 00:29:48 admin in.tftpd[19654]: RRQ from 192.168.80.30 filename debian-installer/amd64/bootnetx64.efi
Nov 20 00:29:49 admin in.tftpd[19654]: tftp: client does not accept options
Nov 20 00:29:49 admin in.tftpd[19655]: RRQ from 192.168.80.30 filename debian-installer/amd64/bootnetx64.efi
Nov 20 00:29:50 admin in.tftpd[19656]: RRQ from 192.168.80.30 filename debian-installer/amd64/grubx64.efi

On the console of the machine I see it say that it's downloaded an
"NBP" then the screen shows:

Welcome to GRUB!

then after a pause it clears and I just have a grub> prompt where I
would normally have expected the installer menu. Therefore I believe
it has correctly downloaded the files it needs, I'm looking at the
running grub from the tftp server, yet something has gone wrong with
the grub configuration.

I have tried both the buster netboot.tar.gz and the daily d-i build
and get the same behaviour with both.

I've also read the relevant part of the release notes:

    https://www.debian.org/releases/buster/amd64/ch04s05.en.html

and they don't tell me anything different than what I've already
done, either.

Any ideas?

Cheers,
Andy