grub2, pxe, and default boot

grub2, pxe, and default boot

[Mahlon E. Smith]

Hey all!  New to the list, and fairly new to Grub2.

I've got about 400+ machines as part of a farm.  They are re-imaged
routinely on demand, each image a different preset for the role it needs
to play (even swapping OS at times.)

Traditionally, we used pxelinux to image this stuff remotely.  I really,
really would prefer to use Grub2 for this, but I've run into a small
problem that I'm hoping the list here can lend a hand with.

The machines are set to network boot as a default.  I'd like to keep
this behavior, and let the timeout fallthrough to the primary hard
drive.  (This way, I can use tftp-hpa to rewrite read requests for
'grubenv' to get per-machine environmental vars, and remote-control the
imaging. That part of this process is working great.)

It looks like I can accomplish this via:

    set root=(hd0,1)
    chainloader +1
    boot


The problem is that there aren't any drives loaded by default from the
(pxe) environment.

    sh:grub> ls
    (pxe)


I discovered that I could 'insmod biosdisk', and lo-and-behold get my
hd* nodes (woo!):

    sh:grub> insmod ext2
    sh:grub> insmod biosdisk
    sh:grub> ls
    (hd0) (fd0) (pxe)


However, I can't actually -use- hd0 for anything.  I'm not sure why.
I'm guessing it has something to do with what filesystem it thinks hd0
is:

    sh:grub> ls -lh
    Device hd0: Filesystem type pxefs    <---- uh oh
    Device fd0: Unknown filesystem
    Device pxe: Filesystem type pxefs

    sh:grub> chainloader (hd0,1)+1
    error: no such partition


... and here's where my diagnostic abilities stop.  :)

Can anyone suggest other things to try, reasons why this might be
happening, or other ways to achieve my goal?  Could this just be a bug?

All input welcome and appreciated.

--
Mahlon E. Smith  
http://www.martini.nu/contact.html

Re: grub2, pxe, and default boot

[Vladimir 'φ-coder/phcoder' Serbinenko]

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Mahlon E. Smith wrote:
>     sh:grub> ls -lh
>     Device hd0: Filesystem type pxefs    <---- uh oh
>   
Upgrade

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



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Re: grub2, pxe, and default boot

[Mahlon E. Smith]

On Tue, May 18, 2010, Vladimir '??-coder/phcoder' Serbinenko wrote:

> Upgrade

Thanks for the speedy reply, Vladimir.  I realized a little bit late
that I had neglected to mention what version I was using.  (1.97.2).

I'll try 1.98 and see how it goes!

--
Mahlon E. Smith  
http://www.martini.nu/contact.html

Re: grub2, pxe, and default boot

[Mahlon E. Smith]

On Tue, May 18, 2010, Vladimir '??-coder/phcoder' Serbinenko wrote:
> Mahlon E. Smith wrote:
> >     sh:grub> ls -lh
> >     Device hd0: Filesystem type pxefs    <---- uh oh
> >
>
> Upgrade


Bumped up to 1.98.  Closer, but still not quite working.

    grub> ls
    (pxe)

    grub> insmod ext2
    grub> insmod biosdisk
    grub> ls -lh
    Device hd0: Partition table
    Device fd0: Unknown filesystem
    Device pxe: Filesystem type pxefs

    grub> ls (hd0,1)/
    error: no such partition.
    grub> chainloader (hd0,1)+1
    error: no such partition.


I'm pretty sure I've got the right partition numbering.  (This is a
VirtualBox tester.)

    # fdisk -l
    Disk /dev/hda: 32.2 GB, 32212254720 bytes
    255 heads, 63 sectors/track, 3916 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

       Device Boot      Start         End      Blocks   Id  System
    /dev/hda1   *           1          16      128488+  83  Linux
    /dev/hda2              17        3916    31326750   8e  Linux LVM



Are my expectations correct with what I'm trying to do here?  Are there
other modules I should be loading via insmod first?

I can't find any info out there on this specific PXE stuff with grub2.
I humbly offer writing up some wiki content in trade for getting this
working. :)

--
Mahlon E. Smith  
http://www.martini.nu/contact.html

Re: grub2, pxe, and default boot

[Vladimir 'φ-coder/phcoder' Serbinenko]

[-- Attachment #1: Type: text/plain, Size: 1877 bytes --]

Mahlon E. Smith wrote:
> On Tue, May 18, 2010, Vladimir '??-coder/phcoder' Serbinenko wrote:
>   
>> Mahlon E. Smith wrote:
>>     
>>>     sh:grub> ls -lh
>>>     Device hd0: Filesystem type pxefs    <---- uh oh
>>>
>>>       
>> Upgrade
>>     
>
>
> Bumped up to 1.98.  Closer, but still not quite working.
>
>     grub> ls
>     (pxe)
>
>     grub> insmod ext2
>     grub> insmod biosdisk
>     grub> ls -lh
>     Device hd0: Partition table
>     Device fd0: Unknown filesystem
>     Device pxe: Filesystem type pxefs
>
>     grub> ls (hd0,1)/
>     error: no such partition.
>     grub> chainloader (hd0,1)+1
>     error: no such partition.
>
>
> I'm pretty sure I've got the right partition numbering.  (This is a
> VirtualBox tester.)
>
>     # fdisk -l
>     Disk /dev/hda: 32.2 GB, 32212254720 bytes
>     255 heads, 63 sectors/track, 3916 cylinders
>     Units = cylinders of 16065 * 512 = 8225280 bytes
>
>        Device Boot      Start         End      Blocks   Id  System
>     /dev/hda1   *           1          16      128488+  83  Linux
>     /dev/hda2              17        3916    31326750   8e  Linux LVM
>
>
>
> Are my expectations correct with what I'm trying to do here?  Are there
> other modules I should be loading via insmod first?
>
>   
You forgot to insmod part_msdos
This mailing list isn't for tech support. Use help-grub or IRC channel
> I can't find any info out there on this specific PXE stuff with grub2.
> I humbly offer writing up some wiki content in trade for getting this
> working. :)
>
> --
> Mahlon E. Smith  
> http://www.martini.nu/contact.html
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



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