Comment 5 for bug 1822007

After additional testing with hardware (instead of in VMs), it looks like things are working fine on Lenovo hardware.

I managed to get access to a Lenovo SR670 server. I deployed it from an existing MAAS, along with a second server (some random node we'll call http-server) to be an HTTP server, since I couldn't update the existing MAAS server to the right commits.

So; http-server was a deployed node from MAAS, on which I simply installed 'apache2'. On that server, I removed index.html from /var/www/html and instead put in bootx64.efi, grubx64.efi, a grub directory with a custom grub.cfg file, and a directory structure copied from MAAS to have a kernel and initrd available. No further actions are required on http-server.

The existing MAAS server was slightly modified to point to the HTTP server: edited /var/lib/maas/dhcpd.conf to add the following snippet (same as in description with the URI updated for http-server):

"""
} elsif option arch = 00:0f {
    # uefi_amd64_http
    filename "http://http-server:80/bootx64.efi";
    option vendor-class-identifier "HTTPClient";
} elsif option arch = 00:10 {
    # uefi_amd64_http
    filename "http://http-server:80/bootx64.efi";
    option vendor-class-identifier "HTTPClient";
"""

Next; the Lenovo SR670 was configured to boot from the network using UEFI HTTP Boot (see https://lenovopress.com/lp0736.pdf); and restarted with a One-time Boot Option; where HTTP Boot was selected.

On the BMC for the Lenovo SR670; one can watch the system boot, request files from HTTP, and potentially show a grub menu or otherwise follow the instructions for booting listed in grub.cfg on http-server.

Watching on http-server, one can see in the apache access.log for requests from the Lenovo SR670:

10.193.36.45 - - [18/Apr/2019:16:10:36 +0000] "HEAD /bootx64.efi HTTP/1.1" 200 211 "-" "UefiHttpBoot/1.0"
10.193.36.45 - - [18/Apr/2019:16:10:36 +0000] "GET /bootx64.efi HTTP/1.1" 200 1335027 "-" "UefiHttpBoot/1.0"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET //grubx64.efi HTTP/1.1" 200 1164875 "-" "UefiHttpBoot/1.0"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/x86_64-efi/command.lst HTTP/1.1" 404 464 "-" "GRUB 2.02-2ubuntu8.13"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/x86_64-efi/fs.lst HTTP/1.1" 404 459 "-" "GRUB 2.02-2ubuntu8.13"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/x86_64-efi/crypto.lst HTTP/1.1" 404 463 "-" "GRUB 2.02-2ubuntu8.13"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/x86_64-efi/terminal.lst HTTP/1.1" 404 465 "-" "GRUB 2.02-2ubuntu8.13"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/grub.cfg HTTP/1.1" 200 338 "-" "GRUB 2.02-2ubuntu8.13"
10.193.36.45 - - [18/Apr/2019:16:10:37 +0000] "GET /grub/grub.cfg-default-amd64 HTTP/1.1" 200 278 "-" "GRUB 2.02-2ubuntu8.13"

This makes me conclude that grub2 does what it is supposed to, and thus any issues might be due to limitations in the EDK2 implementation of HTTP Boot -- possibly some registers or EFI variables are not being updated appropriately. Reassigning to edk2.