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currently, a dell 780 server PXE boots from an image on a 2850 via DHCP server. The problem is, if the 780 is turned on before the 2850, it fails to find the image and hangs. What i need to do is prevent it from hanging. My idea is to install a small distro linux onto the 780, first boot into that. then i can check to see whether or not the 2850 is ready. (using some polling mechanism) when it is, i boot from the image on the 2850.

my question is, is there any way to boot from the pxe boot image from within linux?

If that would be possible, you would have to write to /dev/cmos at a vendor-specific location. I don't know if that is possible with a dell 780, neither where to find a documentation about that BIOS but you should check with DELL.