[syslinux] UEFI syslinux PXE boot issues

Steve Rikli sr at genyosha.net
Wed Aug 16 07:31:50 PDT 2023

On Wed, Aug 16, 2023 at 02:05:33PM +0200, AL13N via Syslinux wrote:
> Joakim Tjernlund schreef op 2023-08-16 13:15:
> > On Thu, 1970-01-01 at 00:00 +0000, AL13N via Syslinux wrote:
> > > 
> > > I'm used to non-UEFI PXE boot, and I use it for my network installer
> > > since forever ago.
> > > 
> > > Looking up how to UEFI PXE boot, I use the syslinux.efi file and
> > > allthough it was loaded and stuff, nothing happend after it, I had at
> > > least expected the ldlinux64 to be requested from the TFTP server, but
> > > nothing.
> > > 
> > > After searching, I noticed someone asking to test the new pre-release,
> > > and so I downloaded the 6.04 version. I replaced the syslinux.efi file
> > > only, and I got a lot more success. I symlinked the pxelinux.cfg dir
> > > and images so it could find the files it needed.
> > > 
> > > Then I got the prompt, I typed "install" to trigger that menu item and
> > > it transferred the vmlinuz file (14sec for 11MB). Then the initrd
> > > (47MB), which takes a long time, but does not ever show the "ok", even
> > > after the transfer was complete (as far as I could tell from the TFTP
> > > server), which takes more than a minute. after some seconds of nothing
> > > happening, it just reboots...
> > > 
> > > Can anyone help met out here?
> > 
> > If I recall correctly, UEFI is somewhat broken. Try iPXE instead.
> I tried to use the iPXE /usr/share/ipxe/ipxe-x86_64.efi, but it had some
> issues with the network card, iirc, I think I saw the network interface
> down, though it likely uses a wrong driver?
> Still, the newer 6.04 one did work, except for loading the large initrd file
> (which took more than 1 minute, which may be the reason it times out?),
> which is probably not UEFI related?

Suggest you try downloading large initrd files with http rather than tftp.

We started having more frequent timeouts during initrd download around the
time RHEL8 became more prevalent in our environment, so we just switched
to http going forward (after CentOS/RHEL 7) since the initrd images seemed
to be on a growth trend over time.

Like you suspect, we generally found this to be a problem independent of
UEFI; it was simply that the modern hardware we were getting was more
frequently coming with UEFI rather than traditional BIOS, and we needed
the newer linux releases to support the newer hardware, etc. so the
situation came together basically at the same time.


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