Comment 13 for bug 1967562

I turned on grub debugging (set debug=all in grub.cfg), and this seems interesting. The "error: couldn't send network packet." message may actually be telling us something is wrong with downloading the initrd. Full log attached, here's a filtered version:

[...]
loader/efi/linux.c:80: UEFI stub kernel:
loader/efi/linux.c:81: PE/COFF header @ 00000040
loader/efi/linux.c:95: LoadFile2 initrd loading enabled
loader/efi/linux.c:459: kernel file size: 46496128
loader/efi/linux.c:461: kernel numpages: 11352
loader/efi/linux.c:478: kernel @ 0xa1e43000
kern/disk.c:196: Opening `tftp,10.229.58.59'...
disk/efi/efidisk.c:482: opening tftp
kern/disk.c:281: Opening `tftp,10.229.58.59' failed.
kern/disk.c:295: Closing `tftp'.
kern/verifiers.c:88: file: /casper/initrd type: 131076
loader/efi/linux.c:396: LoadFile2 initrd loading protocol installed
]
loader/efi/linux.c:141: Installed/updated FDT configuration table @ 0x0
loader/efi/linux.c:191: linux command line: 'BOOT_IMAGE=/casper/vmlinuz
root=/dev/ram0 ramdisk_size=1500000 ip=dhcp
url=http://cdimage.ubuntu.com/ubuntu-server/daily-live/20220408/jammy-live-serv
er-arm64.iso --- debug'
kern/efi/sb.c:111: UEFI Secure Boot state: Disabled
loader/efi/peimage.c:215: PE-COFF header checked
loader/efi/peimage.c:282: sections loaded
loader/efi/peimage.c:493: no relocations
loader/efi/peimage.c:709: Executing image loaded at 0x9f0b0000
Entry point 0xa0fb8428
Size 0x02d90000
EFI stub: Booting Linux Kernel...
EFI stub: Generating empty DTB
loader/efi/linux.c:348: Providing initrd via LOAD_FILE2_PROTOCOL
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
net/net.c:1596: error receiving: 28: couldn't send network packet
error: couldn't send network packet.
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Exiting boot services...