A variety of machines will happily boot a custom bzImage via PXE in legacy mode using syslinux.

In UEFI mode, one of these machines and a newer UEFI only board get assigned an IP address, TFTP syslinx.efi from the server and then freeze.

Now I'm not quite sure why the freeze.

There are no further TFTP requests as seen when using pxelinux.0.

Wireshark shows that the machine is sending the correct PXE/BOOTP extension for an x64 machine PXEClient:Arch:00007:UNDI:003016.

The syslinux.efi binary is x64 build from the 6.03 sources.

Is syslinux.efi even the correct loader? Any thoughts welcomed.

1 Answer 1


The syslinux.efi is the correct loader; unfortunately 6.03 has several issues affecting both UEFI and PXE.

i.e. http://www.syslinux.org/archives/2016-October/025395.html

this is just an example, there are many more issues, like faulty TFTP transfers, bad next-server detection, etc. The patches for all these issues have been submitted and some of them are already merged you should try 6.04-pre1 binaries.

  • Thank you, I should have thought to check!. The 6.04-pre1 binaries work on a Intel Atom Z8350 board but fail on a (relatively ancient) Dell i5-3317. The UEFI mode TFTP is incredibly slow ... 4 minutes for 14MB?
    – J Evans
    Commented Oct 20, 2016 at 15:18
  • 6.04-pre1 is still far from production quality, and you are right the TFTP bug is still there. About your ancient Dell she probably needs a firmware update. If you do not mind running your PXE server in Windows you should give Serva try.
    – Pat
    Commented Oct 20, 2016 at 15:39
  • I ended up using snponly.efi from the iPXE project.
    – clonejo
    Commented Aug 2, 2023 at 17:16

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