Add FILE_API_CHECK to the PXEXT API so the NBP can query the
availability and status of the API.

This allows pxelinux to execute arbitrary gPXE commands.  This is
remarkably unsafe (not least because some of the commands will assume
full ownership of memory and do nasty things like edit the e820 map
underneath the calling pxelinux), but it does allow access to the
"sanboot" command.

stored DHCP packets.

Use generic fields in struct device_description rather than assuming
that the struct device * is contained within a pci_device or
isapnp_device; this assumption is broken when using the undionly
driver.

Add PXENV_UNDI_SET_STATION_ADDRESS.

and matching them up to (e.g. PCI) devices.

lying about in memory, not for loading from ROM), and UNDI net driver.

properly for the PXE UNDI API anyway.

Updated PXE API dispatcher to use copy_{to,from}_user, and moved to
arch/i386 since the implementation is quite architecture-dependent.
(The individual PXE API calls can be largely
architecture-independent.)

shared between TFTP, TFTM and MTFTP protocols.

PXE code now compiles without errors (though it won't actually work).