Merge the pxe_set_netdev()+pxe_[un]hook_int1a() pattern into a single
pxe_[de]activate() call.

pxe_init_structures() fills in the fields of the !PXE and PXENV+
structures that aren't known until gPXE starts up.  Once gPXE is
started, these values will never change.

Make pxe_init_structures() an initialisation function so that PXE
users don't have to worry about calling it.

Grub will include the module name as part of the command line, and
some multiboot kernels expect this to be done.

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

Solaris kernels are multiboot images with the "raw" flag set,
indicating that the loader should use the raw address fields within
the multiboot header rather than looking for an ELF header.  However,
the Solaris kernel contains garbage data in the raw address fields,
and requires us to use the ELF header instead.

Work around this by always using the ELF header if present.  This
renders the "raw" flag somewhat redundant.

This allows gPXE to load memtest86, which is packaged as an old kernel.

Split all code that directly touches the kernel headers out into
bzimage_parse_header() and bzimage_update_header(), to reduce code
size and offset the cost of supporting older kernels.

Total cost of this feature: 11 bytes (uncompressed).

COMBOOT images use INTs to issue API calls; these end up making calls
into gPXE from real mode, and so temporarily change the real-mode
stack pointer.  When our COMBOOT code uses a longjmp() to implement
the various "exit COMBOOT image" API calls, this leaves the real-mode
stack pointer stuck with its temporary value, which causes problems if
we eventually try to exit out of gPXE back to the BIOS.

Fix by adding rmsetjmp() and rmlongjmp() calls (analogous to
sigsetjmp()/siglongjmp()); these save and restore the additional state
needed for real-mode calls to function correctly.

When chaining COMBOOT images, the old images now get freed correctly.

Multi-level menus via COMBOOT rely on the COMBOOT program being able
to exit and invoke a new COMBOOT program (the next menu).  This works,
but rapidly (within about five iterations) runs out of space in gPXE's
internal stack, since each new image is executed in a new function
context.

Fix by allowing tail recursion between images; an image can now
specify a replacement image for itself, and image_exec() will perform
the necessary tail recursion.

Both the script and PXE images types will claim a zero-length image.
Inhibit this to avoid end-user surprises.

Remove the assortment of miscellaneous hacks to guess the "network
boot device", and replace them each with a call to last_opened_netdev().

It still isn't guaranteed correct, but it won't be any worse than
before, and it will at least be consistent.

When trying to find the "first open network device", it helps to
actually check the NETDEV_OPEN flag.

This brings us in to line with Linux definitions, and also simplifies
adding x86_64 support since both platforms have 2-byte shorts, 4-byte
ints and 8-byte long longs.

gcc 4.4 adds another few warnings, and also seems to complain if we
place %ebp in the clobber list for any inline asm.

This function is a major kludge, but can be made slightly more
accurate by ignoring net devices that aren't open.  Eventually it
needs to be removed entirely.

The multiboot specification states that, for raw images, if
load_end_addr is zero then it should be interpreted as meaning "use
the entire file", and if bss_end_addr is zero it should be interpreted
as meaning "no bss".

Add yet another ugly hack to iscsiboot.c, this time to allow the user to
inhibit the shutdown/removal of the iSCSI INT13 device (and the network
devices, since they are required for the iSCSI device to function).

On the plus side, the fact that shutdown() now takes flags to
differentiate between shutdown-for-exit and shutdown-for-boot means that
another ugly hack (to allow returning via the PXE stack on BIOSes that
have broken INT 18 calls) will be easier.

I feel dirty.

We can just treat all non-kernel images as initrds, which matches our
behaviour for multiboot kernels.  This allows us to eliminate initrd as
an image type, and treat the "initrd" command as just another synonym for
"imgfetch".

zImage kernels require the real-mode portion to be loaded at 9000:0000
rather than 1000:0000.

2.6.22+ kernels have an extra field in the bzimage_header structure to
indicate the maximum permitted command-line length.  Use this if it is
available.

Delete ELF as a generic image type.  The method for invoking an
ELF-based image (as well as any tables that must be set up to allow it
to boot) will always depend on the specific architecture.  core/elf.c
now only provides the elf_load() function, to avoid duplicating
functionality between ELF-based image types.

Add arch/i386/image/elfboot.c, to handle the generic case of 32-bit
x86 ELF images.  We don't currently set up any multiboot tables, ELF
notes, etc.  This seems to be sufficient for loading kernels generated
using both wraplinux and coreboot's mkelfImage.

Note that while Etherboot 5.4 allowed ELF images to return, we don't.
There is no callback mechanism for the loaded image to shut down gPXE,
which means that we have to shut down before invoking the image.  This
means that we lose device state, protection against being trampled on,
etc.  It is not safe to continue afterwards.

PXE is a catch-all image format with no signature checks.  If an
unsupported image file is loaded, it will be treated as a PXE image.  In
most cases, the image will be too large to be loaded as a PXE image (which
has to fit in base memory), so the error returned to the user will be that
the segment could not fit within the memory region.

Add an explicit check to pxe_image.c to reject images larger than base
memory with ENOEXEC.

Add ENOEXEC to the error string table.

Allow for settings to be described by something other than a DHCP option
tag if desirable.  Currently used only for the MAC address setting.

Separate out fake DHCP packet creation code from dhcp.c to fakedhcp.c.

Remove notion of settings from dhcppkt.c.

Rationalise dhcp.c to use settings API only for final registration of the
DHCP options, rather than using {store,fetch}_setting throughout.

Add dedicated functions create_dhcpdiscover(), create_dhcpack() and
create_proxydhcpack() for use by external code such as the PXE preboot
code.

Register ProxyDHCP options under the global scope "proxydhcp".

Unregister previously-acquired DHCP and ProxyDHCP settings when DHCP
succeeds.

allowing any space for this, which makes it surprising that bzImage
loading ever worked.

byte, rather than the number of permissible bytes (i.e. subtract one
from the value under the previous definition to get the value under
the new definition).

This avoids integer overflow on 64-bit kernels, where
bzhdr.initrd_addr_max may be 0xffffffffffffffff; under the old
behaviour we set mem_limit equal to initrd_addr_max+1, which meant it
ended up as zero.  Kernel loads would fail with ENOBUFS.

otherwise.  :(

Some shuffling around of the image management code; this needs tidying up.

list.

Added FEATURE() macros to most relevant (non-driver) files.

bytes of useless zeroes in the final image.

by PXE and NBI) and UNDI packets (as used by undinet and UNDI).

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.

pointer to it.

Implement PXENV_RESTART_TFTP.