[syslinux] current state of pxelinux for UEFI...

Frantisek Rysanek Frantisek.Rysanek at post.cz
Thu Nov 7 14:06:04 PST 2019

Dear gentlemen,

I think I'd better start another thread for this...
thanks to Ady Ady and Gregory Lee Bartholomew for their responses to 
my early question.

Just for the record, my fresh experience with PXElinux 6.x follows:

syslinux.efi version 6.03 does boot to the extent that it shows a 
prompt, but if I provide it with a CFG file containing several 
labels, no matter what label I type at the boot prompt, it always 
loads the default label :-)

And, it then croaks about incorrect signature... and yes I do have 
secure boot disabled in the BIOS. It sure won't start any .efi 
exectuable that I've tried (such as ipxe.efi or memtest.efi or the 
rEFInd, which OTOH is not a surprise, as this is not supposed to 
work). I believe I've noticed Ady Ady's earlier message that 
chain-loading further bootloaders does not work.
If I try to load a kernel and an initrd, it takes ages to load them, 
and apparently syslinux then hangs once the two files get loaded, 
there's never any further message.
Do I need to modify the standard kernel bzImage in any way, for it to 
be UEFI-bootable via PXElinux or Grub2 ?

Next I tried the current latest GIT "master".
That doesn't even get as far as showing a prompt.
I'm attaching a log snippet from the TFTP server.
Apparently it loads the syslinux.efi, then it loads the syslinux.efi 
again, then it loads the ldlinux.e64 (prepared at the path where it's 
looking for it), and then tries to load that same file ldlinux.e64 
again, over and over several times, as if the first load attempt 
failed... I believe the PXE stack actually flashes a message that it 
has loaded the boot file, but that message vanishes in a fraction of 
a second and then it gets stuck with just about two text lines, as if 
nothing got loaded...

Tomorrow I'll try the branch prepared by Sebastian Herbszt, mentioned 

I've also found Gregory's patch here:
If I understand this correctly, it doesn't fix the buggy strncat 
Gregory has mentioned - the patch adds support for another boot image 
format called BLS1 (now becoming popular).
There's probably no point for me to try to apply this patch...

I've also tried looking at the binaries available from Debian testing 
packages "pxelinux" and "syslinux-common"... and it seems to me that 
the "pxelinux" package only contains binaries for the legacy BIOS 
PXE, and the "syslinux-common" contains just the c32 modules for all 
three flavours (BIOS/UEFI32/UEFI64) but no syslinux.efi... 

Any response would be welcome :-)

So far I've been trying with one particular board by AsRock.
I should probably try other motherboards too, for comparison.
I have other hardware around, where a UEFI-flavoured PXE stack
is an option (besides legacy PXE) or where UEFI PXE is the only way.
I may test them later as I get the boxes or boards in my hands.
I work in a "computer hardware toy store" and I tend to use Linux for 
some diagnostic tasks - hence my motivation to have a netboot 
environment in the LAN.

Frank Rysanek

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