[gPXE] Upgrading gPxe boot protocol from 2.07 to 2.08 ?

[Laurent Eschenauer]

Hi all,

Below is a kinda crazy idea that I'm working on, and I'm now stuck due to
my gPxe kernel not having the 'boot protocol' >= 2.08. I'm not a kernel
guru; so I hope someone on this list may have some ideas/pointers to move
forward.

*The context:*
I'm trying to create an Amazon EC2 AMI that just boots a gPxe kernel which
then chain to the EC2 user data to get its pxe configuration. This would
enable to directly provision any kind of machine on EC2 using pxe, removing
the hassle of building/uploading images. Kickstart based install also
enable to customize the partition table, the packages, etc..

*What I did so far:*
EC2 (which is Xen based) enable to boot on custom kernels (using pv-grub).
So I managed to build the right volume, with proper grub configuration to
boot on the gpxe.lkrn (build from latest sources on git). When I boot on
this kernel, here is what EC2 provides me as output:

kernel /boot/gpxe.krn

ERROR Invalid kernel: xc_dom_probe_bzimage_kernel: boot protocol too old
(0207) xc_dom_bzimageloader.c:351: panic: xc_dom_probe_bzimage_kernel: boot
protocol too old (0207)

ERROR Invalid kernel: xc_dom_find_loader: no loader found
xc_dom_core.c:523: panic: xc_dom_find_loader: no loader found
xc_dom_parse_image returned -1

*The problem:*
Digging into xen source for this error [1], I realized that the xen loader
used on EC2 only supports kernel packaged with a boot protocol greater or
equal to 2.08 [2]. And from the error message, it seems the current boot
protocol in gPxe is 2.07. I could also verify this in the source code [3].

This is where I'm stuck, having no clue on how to update gPxe boot
protocol, what it actually means, if this has been done, or if even
remotely possible.

Any pointers/ideas appreciated !

Cheers,

Laurent

[1] https://gist.github.com/2000467 (see line 102)
[2] http://www.mjmwired.net/kernel/Documentation/x86/boot.txt#46
[3]
http://git.etherboot.org/gpxe.git/blob/HEAD:/src/arch/i386/prefix/lkrnprefix.S#l122
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