UEFI PXE boot

Spike_White at Dell.com Spike_White at Dell.com
Thu Jul 26 13:13:48 CDT 2012


I'm not understanding how this is a bug in 11th gen servers.  Rather a limitation of that firmware's user interface.

PXE boot implies a BIOS boot.  I PXE-boot all the time at my house into CentOS, Ubuntu or OEL.  Using pxelinux (with pxelinux.0 as my NBP).

Also, we have PXE boot set up in our labs for our server builds.  It's a more complicated back-end infrastructure, but the same phases.  DHCP -> TFTP -> download NBP -> off to the races.

UEFI network boot is a different animal.    Luckily, UEFI network boots can re-use our existing DHCP/TFTP infrastructure we've already set up.  But it's a totally different NBP and it's the boot client doing a UEFI boot instead of a BIOS boot.  

Here's a good reference for re-using existing PXE infrastructure for a network UEFI boot:

     http://docs.fedoraproject.org/en-US/Fedora/17/html/Installation_Guide/s1-netboot-pxe-config-efi.html   

So in this example, it's pxelinux/bootx64.efi that's the network boot program.  (Appears to be the /install/images/efiboot.img out of the CentOS 6.2 DVD.)

On a 12th gen server (like a M620 or R620) you can go into boot manager (F11) and interactively select a UEFI boot or a BIOS boot.  If you want PXE, you select BIOS boot.

On a 11th gen server (like a R710), F11 by default is the BIOS boot manager.  If you press F2 and go to Boot settings, you can change the boot mode to UEFI.  Then if you reboot, F11 is the UEFI boot manager.  But then you can't PXE boot (as PXE boot implies a BIOS boot).

Internally,  if attempting a UEFI network boot, a Dell 11g or 12g server sends this Vendor Class Identifier (VCI):

    PXEClient:ARCH:00007:UNDI:00301

If attempting a PXE boot, the client sends this VCI:

    PXEClient:Arch:00000:UNDI:002001

A smart DHCP server can key off that VCI and set up the DHCP option 67 (boot filename) appropriately.  As they do in the example above.

Spike



Where 

> ------------------------------
> 
> Message: 2
> Date: Thu, 26 Jul 2012 08:53:39 -0800
> From: Erinn Looney-Triggs <erinn.looneytriggs at gmail.com>
> Subject: Re: UEFI PXE boot
> To: linux-poweredge at lists.us.dell.com
> Message-ID: <50117613.8000809 at gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> To continue on with this somewhat Red Hat support has now duplicated the
> failure to PXE boot with UEFI enabled, on an R610 (in my testing r510
> and r710 systems fail as well) and is working with Dell on a resolution
> to the issue. No idea how long that will take.
>
> -Erinn




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