[Bug]: Regression: PXE boot for EFI clients broken

[koppd]

Version

7.1.12

Host OS Type

Linux

Host OS name + version

openSUSE Tumbleweed

Host Architecture

x86

Guest OS Type

Linux

Guest Architecture

x86

Guest OS name + version

openSUSE Leap 15.6

Component

EFI

What happened?

Booting a VM (EFI with PXE boot) fails very soon before e.g. GRUB can take over.

The boot screen looks like this:

>>Start PXE over IPv4.
  Station IP address is 172.16.0.11

  NBP filename is /openSUSE-Leap-15.6-x86_64/net/x86_64-efi/

  NBP filesize is 965672 Bytes
 Downloading NBP file...
 
 NBP file downloaded successfully.
Fetching Netbott Image (openSUSE-Leap-15.6-x86_64/net/x86_64-efi/revocations.efi
Unable to fetch TFTP image: TFTP Error
Fetching Netboot Image (openSUSE-Leap-15.6-x86_64/net/x86_64-efi/grub.efi

And then it hangs. It looks like an infinite loop because one CPU core is utilized at 100%.

Hints

The changelog of VirtualBox 7.1.4 says:
EFI: Restored broken network boot support (7.1.0 regression)
=> maybe it is not fully restored. (or it is only for Windows clients?)

My test cases:

• Linux host with VirtualBox 7.1.12: broken
• Windows 11 host with VirtualBox 7.1.12: broken
• Windows 11 host with VirtualBox 7.0.26: works(!)
• Exporting and importing into VMware Workstation 17.6.3 (Windows 11): works

BIOS mode

VMs with BIOS instead of EFI are not affected by this regression. They can PXE boot. Of course, the TFTP files are different.

Logs

OS Boot2 UEFI-Klon2-2025-08-11-21-34-11.log

How can we reproduce this?

Well, this could be tricky.
First, you need to set up a DHCP server who is reacting on client this DHCP option 60 (PXEclient).
This server must provide the client with the name of the first boot file, bootx64.efi.
Secondly, you need a TFTP server to provide all necessary files (grub.cfg, image data and so on.) to the client. And all the config file stuff.

I used the information from: https://www.suse.com/c/step-by-step-instructions-for-building-a-multiple-architecture-opensuse-leap-pxe-server/

Did you upload all of your necessary log files, screenshots, etc.?

• Yes, I've uploaded all pertinent files to this issue.

[AlexanderEichner]

This works fine locally with the virtio-net device but I'm using bridged networking to be able to use my local PXE/TFTP server. As it seems that the TFTP server is returning an error can you cerate a network trace using the following commands?
VBoxManage controlvm <VM name> nictracefile1 <path/to/pcap>
VBoxManage controlvm <VM name> nictrace1 on

[koppd]

test1.zip

Here is the network trace. As far a I can see both files (bootx64.efi and grub.efi) are fully transferred.

[AlexanderEichner]

The revocations.efi failed to transfer but that seems to be expected because it isn't there. My current assumption is that the grub.efi is causing this issue, can you please upload the file which "/openSUSE-Leap-15.6-x86_64/net/x86_64-efi/grub.efi" points to?

[koppd]

grub.zip

I noticed that the version 7.2.0 of VirtualBox has been released. The change log mentions:

• UEFI: Added workaround for Grub bug causing guest OS crashes

I've run a test (Windows 11 Host and same Linux Clients) and the issue has been resolved!