[syslinux] EFI booting over network - can't then load anything

[Spike White]

On 06/09/2014 12:09 AM, Andrew Rae wrote:
>
> Many thanks!
>
> I think we thought that it was more functional in EFI mode than it is -
apologies !
>
> I/We tried to do a RedHat 7 RC UEFI Network Boot - and that seemed to
work OK & as expected....
> If we could only get Centos 6.5 and some version of WindowsPE to boot! -
we could switch to using EFI booting on the new pc's/laptops to image them
up!
>
> Thanks - I'll keep my eye on the mailing list & try it on a few of the
newer releases as they come out
> Andrew

Andrew,

Yesterday I tested on OL 6.5 (Redhat-compatible kernel).  So like Centos
6.5,
Oracle Linux is merely a re-spin of RHEL6.5.  Tried on physical hardware.
 As
you say, the computer crashes and reboots.  This was syslinux 6.03-pre6.

But does crashes in an interesting place.  *After* it loads kernel and
seemingly the full initramfs.

Then I tested against the bootx64.efi NBP supplied with grub2. CentOS 6.5
will
EFI PXE boot with that NBP. bootx64.efi bootloader Gives an interesting
message:

   trying to allocate 1000 pages for vmlinuz

Also yesterday, Redhat released RHEL7 (GA version).  Today I tested that.

RHEL7 itself bundles kernel version 3.10, so I assume the boot media's
vmllinuz
is of comparable vintage.

As H. Peter predicted, syslinux.efi NBP boots the RHEL7 install media.
(It's a
new enough kernel).

So -- if we ignore this problem long enough (syslinux.efi can't EFI PXE boot
ancient kernels) -- the problem will go away.

In the meantime, the grub2 bootx64.efi bootloader will EFI PXE boot these
archaic kernels.

I'm curious how grub2's bootx64.efi bootstraps these older kernels.

Spike