[gPXE] GRUB 1.97 PXE

[Paul Geraedts]

Hi Marty,

Nice to hear that you're interested. Today I subscribed to the
gpxe at etherboot.org list.

AFAIK the PXE version of GRUB2 starts by creating a '(pxe)' device and
sets the root directory to this (pxe) device (basically 'root (pxe)').
Then it searches in /boot/grub/ of this device for its configuration
file ('grub.cfg') and module files ('*.mod'), among others. If it
doesn't find those files, you end up in rescue mode. This rescue mode
is limited in functionality, but does allow for commands like 'ls',
which does not show the (pxe) device when I boot from gPXE. So for
some reason GRUB2 doesn't seem able to create this (PXE) device right
after it gets loaded by gPXE. It does create this (PXE) device when
loaded by my proprietary boot ROM, after which it successfully enters
the normal mode.

What I understand is that GRUB2 will - in the short-term (v2.00?) -
have full-featured support for booting from optical discs and USB
devices even if the BIOS doesn't support those. Sounds to me like a
handy feature in case of certain emergencies regarding older
computers. So GRUB2 seems an interesting candidate to netboot first
off my WRT54GL router.

That is, when I've got some more time I will add an SD card slot on
this router. (AFAIK it can be connected by means of SPI over GPIO,
which seems to be supported by OpenWrt.) Then I only have to add
appropriate EEPROMs to the RTL8139D cards in boths my servers, and my
complete netboot environment should be up-and-running (my laptops can
use their build-in PXE ROM for the moment). I got some remaining
questions on this hardware side of gPXE, but that's something for
another thread.

Looking forward to any developments on GRUB2 compatibility.

Cheers,

Paul


2009/11/4 Marty Connor <mdc at etherboot.org>:
> Hi Paul,
>
> I approved your post to the gPXE mailing list.  Please join the list if you
> would like to continue sending and receiving messages to the list.
>
> At the moment we're in a transition from the old Etherboot-Discuss and
> Etherboot-Developer lists to the new gpxe at etherboot.org list. You might also
> want to join Etherboot-Discuss for the short term until we do the official
> switchover (which should be within a week or two)
>
> Your question is an interesting one, and we are working on better PXE
> compatibility right now.  We recently been in contact with the author of
> DNSMasq about compatibility.
>
> I'm not quite sure I understand how this is supposed to work, and the
> difference in behavior between other PXE implementations and gPXE.  I'm sure
> we can find out with a little debugging, and we're interested in doing so.
>
> gPXE stands for GPL'ed PXE.  When I came up with the name I was mostly
> looking for something that emphasized that we were doing a FOSS PXE
> implementation, so I followed the pattern of various other things like gcc,
> gawk, gnus, etc.
>
> Thanks again for your report, and I would like to see if we can understand
> what is causing the difference in behavior you are seeing between PXE
> implementations.
>
> Regards,
>
> Marty
>
> Paul Geraedts wrote on 11/3/09 7:31 PM:
>>
>> Hello,
>>
>> First of all, thanks for all the effort you all put in Etherboot/GPXE
>> (I've much enjoyed your Google Tech Talk Video). I recently started
>> using GPXE and it simply is a great tool! I already used various GPXE
>> features successfully.
>>
>> The one thing I can't seem to get to work though is the combination of
>> GPXE and the PXE version of GRUB2 (the latest v1.97 to be precise). I
>> followed the instructions on http://grub.enbug.org/PXEBOOT to build
>> the GRUB PXE image and used DNSmasq in Ubuntu (Karmic) to serve the
>> image to the client side (my laptop). It works with the build-in PXE
>> ROM in my laptop, but it doesn't seem to work with GPXE. (To be
>> precise: GRUB only wants to start in rescue mode in the latter case).
>> Am I doing something wrong, or is there some sort of incompatibility
>> between the two tools?
>>
>> Any help on this is much appreciated.
>>
>> Cheers, Paul
>>
>>
>> BTW, what does the G in GPXE actually stand for?
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>