[syslinux] Can't UEFI boot PXELinux on WDS server

[Ady]

> DHCP seems to be working properly - returning the correct boot file for the
> architecture of the PXE client, but when I try to boot syslinux.efi, it gets
> the file then keeps requesting ldinux.e64 over and over again.  The file is
> there and available.  A wireshark trace shows it keeps requesting the file,
> followed by the server responding to the blksize and tsize options, but then
> the client just continues requesting the file.   After a few dozen failed
> attempts it then tries to get the boot\x64\/boot/isolinux/ldlinex.e64 file
> for a few dozen more tries.
> 
 
I am not sure what you meant with "returning the correct boot file 
for the architecture of the PXE client". A UEFI IA32 client 
(architecture-type = 00:06) should look for the syslinux.efi file 
from efi32 (which then looks for ldlinux.e32), and similarly for UEFI 
x86_64 (syslinux.efi + ldlinux.e64). The file can be renamed (e.g. to 
bootia32.efi, bootx64.efi) if the dhcp configuration is also changed 
accordingly. What I mean is that the syslinux.efi file _is_ the "boot 
file", so what "boot file for the architecture of the PXE client" you 
are referring to?.

Regarding the path you mentioned, the "isolinux" part seems strange. 
There is no "isolinux" in UEFI. I have seen such misunderstanding 
before, so you are not the only one. I am not saying that you cannot 
use such pathprefix, but I would suggest avoiding such potential 
confusion.

FWIW, there is also a typo in your report (ldlinex.e64 should be 
ldlinux.e64).

And the most important detail... Are you using Syslinux 6.03 final? 
Or is this a pre-prelease? Are you using the official upstream 
pre-built binaries downloaded from kernel.org? Or are you using some 
distro package? Or perhaps your own build?

Please try the official upstream pre-built binaries from version 6.03 
final, and remember that any version mismatch (e.g. between 
syslinux.efi and ldlinux.e64 and additional c32 files) shall be 
avoided.

Regards,
Ady.