[ipxe-devel] Question Regarding ipxe/gpxe

Michael Brown mbrown at fensystems.co.uk
Wed Mar 30 23:31:02 UTC 2011

On Wednesday 30 Mar 2011 23:38:04 Matthew Hoey wrote:
> Normally at this point we should go through the boot process and not find
> the script so we boot to disk. However, there are some problematic servers
> with our BIOS settings incorrect which has them boot off of NIC1 and these
> particular servers don't handle the lack of DHCP very well. It'd be great
>  if we should just alter the script to force it to boot straight to the
>  hard drive. I was hoping the kernel and initrd commands would have the
>  ability to call it's own hard drive, but I know that sort of defeats the
>  purpose of network booting.

If you can wait a week or so, you might be in luck.  One of the features on my 
current ToDo list is to expose the separate SAN hook/unhook/boot actions that 
have been possible since the internal block-device API redesign back in 

The expected usage would be to hook a SAN device and then boot from it.  The 
commands will almost certainly use BIOS drive numbers to refer to the SAN 

You should therefore be able to issue a command to boot from the SAN device at 
BIOS drive 0x80 *without* having actually hooked in a SAN device.  This should 
cause the machine to boot from the local disk without exiting iPXE.

The downside is that iPXE will still be resident in RAM, as with a normal SAN 
boot, so you'll lose a small amount of memory, but it should do what you're 
looking for.

You can use the attached patch to try out this "boot local disk from iPXE" 
approach.  Please please please do not deploy this patch in production code; 
this is just to let you test whether or not the real fix (which should happen 
within a week) will work for you.

> Our machines image by looking for a script on our TFTP server. After we've
> finished laying down an image on the disk we clear the script file and
> reboot.

You might be interested in the "prompt" command, which would save you from 
having to change anything on the TFTP server.  It lets you create a script 
that implements a boot prompt such as

  Press F12 within 2 seconds to install from network...

and skip the installation unless the user presses F12 (or whatever key you 
want to use).  See the documentation at http://ipxe.org/cmd/prompt for 

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