These commands can be used to activate or deactivate the PXE API (on a
specifiable network interface).

This is currently of limited use, since most image formats will call
shutdown() before booting the image, meaning that the underlying net
device gets shut down during remove_devices() anyway.

PXENV_STOP_UNDI should return PXENV_STATUS_KEEP_UNDI if the UNDI
cannot be safely unloaded (e.g. due to interrupt vectors that could
not be unhooked).

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.

It is possible that the UNDI ISR may be triggered before netdev_tx()
returns control to pxenv_undi_transmit().  This means that
pxenv_undi_isr() may see a zero undi_tx_count, and so not check for TX
completions.  This is not a significant problem, since it will check
for TX completions on the next call to pxenv_undi_isr() anyway; it
just means that the NBP will see a spurious IRQ that was apparently
caused by nothing.

Fix by updating the undi_tx_count before calling netdev_tx(), so that
pxenv_undi_isr() can decrement it and report the TX completion.

Symantec Ghost requires working multicast support.  gPXE configures
all (sufficiently supported) network adapters into "receive all
multicasts" mode, which means that PXENV_UNDI_SET_MCAST_ADDRESS is
actually a no-op, but the current implementation returns
PXENV_STATUS_UNSUPPORTED instead.

Fix by making PXENV_UNDI_SET_MCAST_ADDRESS return success.  For good
measure, also implement PXENV_UNDI_GET_MCAST_ADDRESS, since the
relevant functionality is now exposed by the net device core.

Note that this will silently fail if the gPXE driver for the NIC being
used fails to configure the NIC in "receive all multicasts" mode.

The PXE debugging messages have remained pretty much unaltered since
Etherboot 5.4, and are now difficult to read in comparison to most of
the rest of gPXE.

Bring the pxe_undi debug messages up to normal gPXE standards.

Signed-off-by: Michael Brown <mcb30@etherboot.org>

The Symantec UNDI DOS driver fails when run on top of gPXE because we
return our interface type as "gPXE" rather than one of the predefined
NDIS interface type strings.

Fix by returning the standard "DIX+802.3" string; this isn't
necessarily always accurate, but it's highly unlikely that anything
trying to use the UNDI API would understand our IPoIB link-layer
pseudo-header anyway.

The Intel DOS UNDI driver fails when run on top of gPXE because we do
not fill in the ServiceFlags field in PXENV_UNDI_GET_IFACE_INFO.

Fix by filling in the ServiceFlags field with reasonable values
indicating our approximate feature capabilities.

The 3Com DOS UNDI driver fails when run on top of gPXE for two
reasons: firstly because PXENV_UNDI_SET_PACKET_FILTER is unsupported,
and secondly because gPXE enters the NBP without enabling interrupts
on the NIC, and the 3Com driver never calls PXENV_UNDI_OPEN.

Fix by always returning success from PXENV_UNDI_SET_PACKET_FILTER
(which is no worse than the current situation, since we already ignore
the receive packet filter in PXENV_UNDI_OPEN), and by forcibly
enabling interrupts on the NIC within PXENV_UNDI_TRANSMIT.  The latter
is something of a hack, but avoids the need to implement a complete
base-code ISR that we would otherwise need if we were to enter the NBP
with interrupts enabled.

In order to construct outgoing link-layer frames or parse incoming
ones properly, some protocols (such as 802.11) need more state than is
available in the existing variables passed to the link-layer protocol
handlers. To remedy this, add struct net_device *netdev as the first
argument to each of these functions, so that more information can be
fetched from the link layer-private part of the network device.

Updated all three call sites (netdevice.c, efi_snp.c, pxe_undi.c) and
both implementations (ethernet.c, ipoib.c) of ll_protocol to use the
new argument.

Signed-off-by: Michael Brown <mcb30@etherboot.org>

Signed-off-by: Michael Brown <mcb30@etherboot.org>

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.

Etherboot 5.4 erroneously treats PXENV_UNLOAD_STACK as the "final
shutdown" call, and unhooks INT15.  When using gPXE's undionly.kpxe,
this results in gPXE overwriting the portion of Etherboot located in
high memory, because it is no longer hidden from the system memory map
at the time that gPXE loads.

Work around this by explicitly testing for Etherboot as the underlying
PXE stack (as is already done in undinet.c) and skipping the call to
PXENV_UNLOAD_STACK if necessary.

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.

The build mechanism currently allows for multiple objects per source
file.  The only remaining user of this is unnrv2b.S.  Replace this
usage with a separate unnrv2b16.S wrapper file, as is currently used
for e.g. pxeprefix.S and kpxeprefix.S.

Some utilities that expect a floppy disk image (e.g. iLO?) may test
for a file of the correct size.  Reinstate the .pdsk image format in
order to provide this if needed.

QEMU will silently round down a disk or ROM image file to the nearest
512 bytes.  Fix by always padding .rom, .dsk and .hd images to the
nearest 512-byte boundary.

Originally-fixed-by: Stefan Hajnoczi <stefanha@gmail.com>

Using "lret $2" to return from an interrupt causes interrupts to be
disabled in the calling program, since the INT instruction will have
disabled interrupts.  Instead, patch CF on the stack and use iret to
return.

Interestingly, the original PC BIOS had this bug in at least one
place.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Michael Brown <mcb30@etherboot.org>

This is required in order to build on Mac OS X.

Modified-by: Michael Brown <mcb30@etherboot.org>
Signed-off-by: Michael Brown <mcb30@etherboot.org>

When handling a redirection event, we need to close the existing
connection before opening the new connection.

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).

Modified-by: Michael Brown <mcb30@etherboot.org>
Signed-off-by: Michael Brown <mcb30@etherboot.org>

The parsing of the !PXE and PXENV+ structures share a fair bit of
code; merge the common code to save a few bytes.

Signed-off-by: Michael Brown <mcb30@etherboot.org>

This is not strictly an entry requirement, but it does mean that a PXE
NBP returning without setting %ax will appear to have returned
success.

Search for the PXE entry points (via the !PXE or PXENV+ structures)
through all known combinations of search methods.  Furthermore, if we
find a PXENV+ structure, attempt to use it to find the !PXE structure
if at all possible.

Avoid passing credentials in the iBFT that were available but not
required for login.  This works around a problem in the Microsoft
iSCSI initiator, which will refuse to initiate sessions if the CHAP
password is fewer than 12 characters, even if the target ends up not
asking for CHAP authentication.

The PXE 1.x spec specifies that on NBP entry or on return from INT
1Ah AX=5650h, EDX shall point to the physical address of the PXENV+
structure.  The PXE 2.x spec drops this requirement, simply stating
that EDX is clobbered.  Given the principle "be conservative in what
you send, liberal in what you accept", however, we should implement
this anyway.

Certain combinations of PXE stack and BIOS result in a broken INT 18
call, which will leave the system displaying a "PRESS ANY KEY TO
REBOOT" message instead of proceeding to the next boot device.  On
these systems, returning via the PXE stack is the only way to continue
to the next boot device.  Returning via the PXE stack works only if we
haven't already blown away the PXE base code in pxeprefix.S.

In most circumstances, we do want to blow away the PXE base code.
Base memory is a limited resource, and it is desirable to reclaim as
much as possible.  When we perform an iSCSI boot, we need to place the
iBFT above the 512kB mark, because otherwise it may not be detected by
the loaded OS; this may not be possible if the PXE base code is still
occupying that memory.

Introduce a new prefix type .kkpxe which will preserve both the PXE
base code and the UNDI driver (as compared to .kpxe, which preserves
the UNDI driver but uninstalls the PXE base code).  This prefix type
can be used on systems that are known to experience the specific
problem of INT 18 being broken, or in builds (such as gpxelinux.0) for
which it is particularly important to know that returning to the BIOS
will work.

Written by H. Peter Anvin <hpa@zytor.com> and Stefan Hajnoczi
<stefanha@gmail.com>, minor structural alterations by Michael Brown
<mcb30@etherboot.org>.

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.

The version of the GNU assembler shipped with Fedora 10
(2.18.50.0.9-8.fc10) complains about character literals in some of our
assembly code.  Changing $'x' to $( 'x' ) seems to fix the problem.
Yes, the whitespace is required; using just $('x') does not work.

Reported by Kevin O'Connor <kevin@koconnor.net>.

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

There are code paths other than PMM allocation that can result in our
changing the ROM checksum.  For example, we attempt to update our
product string to incorporate the PCI bus:dev.fn number.  In a system
that does not support PMM, we could therefore end up with an incorrect
checksum.

Fix by attempting to update the checksum unconditionally.

Try to avoid future problems caused by implicit section flags and/or
type information by instituting a policy that all .section
declarations must explicitly state the flags and type.

Most of this change was achieved using

    perl -pi \
      -e 's/".text"$/".text", "ax", \@progbits/ ; ' \
      -e 's/".text16"$/".text16", "ax", \@progbits/ ; ' \
      -e 's/".text16.null"$/".text16.null", "ax", \@progbits/ ; ' \
      -e 's/".text16.data"$/".text16.data", "aw", \@progbits/ ; ' \
      -e 's/".data"$/".data", "aw", \@progbits/ ; ' \
      -e 's/".data16"$/".data16", "aw", \@progbits/ ; ' \
      -e 's/".bss"$/".bss", "aw", \@nobits/ ; ' \
      -e 's/".bss16"$/".bss16", "aw", \@nobits/ ; ' \
      -e 's/".prefix"$/".prefix", "ax", \@progbits/ ; ' \
      -e 's/".prefix.lib"$/".prefix.lib", "awx", \@progbits/ ; ' \
      -e 's/".prefix.data"$/".prefix.data", "aw", \@progbits/ ; ' \
      -e 's/".weak"$/".weak", "a", \@nobits/ ; ' \
      `git grep -l '\.section'`

As reported by Stefan, commit 13d09e6 ("[i386] Simplify linker script
and standardise linker-defined symbol names") breaks gdb, readelf and
associated utilities.

This is caused by the .stack section overwriting a block in the middle
of the .debug_info section (despite being included in the
.bss.textdata section in the output file, which apparently has the
correct attributes for a .bss section).

Fixed by adding explicit flags and type to the stack section
declaration.