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.

Shifting all INT13 drive numbers causes problems on systems that use a
sparse drive number space (e.g. qemu BIOS, which uses 0xe0 for the CD-ROM
drive).

The strategy now is:

  Each drive is assigned a "natural" drive number, being the next
  available drive number in the system (based on the BIOS drive count).

  Each drive is accessed using its specified drive number.  If the
  specified drive number is -1, the natural drive number will be used.

  Accesses to the specified drive number will be delivered to the
  emulated drive, masking out any preexisting drive using this number.

  Accesses to the natural drive number, if different, will be remapped to
  the masked-out drive.

The overall upshot is that, for examples:

  System has no drives.  Emulated INT13 drive gets natural number 0x80
  and specified number 0x80.  Accesses to drive 0x80 go to the emulated
  drive, and there is no remapping.

  System has one drive.  Emulated INT13 drive gets natural number 0x81
  and specified number 0x80.  Accesses to drive 0x80 go to the emulated
  drive.  Accesses to drive 0x81 get remapped to the original drive 0x80.

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".

__from_data16 and __from_text16 now take a pointer to a
.data16/.text16 variable, and return the real-mode offset within the
appropriate segment.  This matches the use case for every occurrence
of these macros, and prevents potential future bugs such as that fixed
in commit d51d80f.  (The bug arose essentially because "&pointer" is
still syntactically valid.)

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

When the 16-bit segment registers are accessed using 32-bit instructions
the high order bytes are undefined on older CPUs.  We now explicitly
zero the high order bytes when snapshotting the CPU state.  This ensures
that the GDB stub reports consistent values for the segment registers.

Commit fd0aef9 introduced a typo that caused PMM detection to start at
paragraph 0xe00 rather than 0xe000.  (Detection would still work, since it
would scan until it ran out of base memory, but it would end up scanning
an unnecessarily large portion of base memory.)

Spotted by Sebastian Herbszt <herbszt@gmx.de>.

Send a null command, specifically "pulse outputs" with no outputs
selected, to the KBC after changing A20.  This was apparently done by DOS,
presumably as a synchronization hack, and the authors of the UHCI spec
thought it was inherent.  Therefore, there are systems out there (e.g. HP
DL360 G5) which will stop responsing to "legacy USB" unless they see the
null command, 0xFF, written to port 0x64 at the end of the A20 toggling
sequence.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

If we ever need these macros, they should be defined in
include/{big,little}_bswap.h, and the whole family should be defined.

When the BIOS doesn't support BBS, hooking INT 19 is the only way to add
ourselves as a boot device.  If we have to do this, we should at least
try to chain to the original INT 19 vector if our boot fails.

Idea suggested by Andrew Schran <aschran@google.com>

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.

A bug in read_smbios_string() was causing the starting offset of the
SMBIOS structure to be added twice, resulting in completely the wrong
strings being returned.

Bug identified by Martin Herweg <m.herweg@gmx.de>

We never set up specific multicast filters; native drivers will ask
the card to receive all multicast packets.  The only way to achieve
this via the UNDI API is to enable promiscuous mode.

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.

See http://etherboot.org/wiki/dev/gdbstub for documentation.

The GDBSYM config.h option was an attempt at QEMU GDB debugging.  I have
removed the code since it is unused and may confuse people wanting to
use the GDB stub.

The ROM prefix now prompts the user to enter the gPXE shell during POST;
this allows for configuring gPXE without needing to attempt to boot from
it.  (It also slows down system boot by three seconds per gPXE ROM, but
hey.)

This is apparently a certain OEM's requirement for option ROMs.

This allows multiple gPXE ROMs in a system to be disambiguated at boot
time; the PCI ID will show up in the boot menu for a BBS-compliant BIOS.

Add ability for network devices to flag link up/down state to the
networking core.

Autobooting code will now wait for link-up before attempting DHCP.

IPoIB reflects the Infiniband link state as the network device link state
(which is not strictly correct; we also need a succesful IPoIB IPv4
broadcast group join), but is probably more informative.

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.

In particular, expose the system UUID as a setting ("smbios/uuid").

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

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.

The home-grown versions don't work properly for static variadic
functions, when gcc can choose to use a non-standard calling convention.

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.

Minor bugfix: 4 x 2 = 8, not 16

When PMM is used, the gPXE image source will no longer be in base memory.
Decompression of .text16 and .data16 can therefore no longer be done in
real mode.

Use BBS installation check to see if we need to hook INT19 even on a PnP
BIOS.

Verify that $PnP signature is paragraph-aligned; bochs/qemu BIOS provides
a dummy $PnP signature with no valid entry point, and deliberately
unaligns the signature to indicate that it is not properly valid.

Print message if INT19 is hooked.

Attempt to use PMM even if BBS check failed.

Move the printing functions from pxeprefix.S into libprefix.S, so they
are available for debug from any prefix.

ROM initialisation vector now attempts to allocate a 2MB block using
PMM.  If successful, it copies the ROM image to this block, then
shrinks the ROM image to allow for more option ROMs.  If unsuccessful,
it leaves the ROM as-is.

ROM BEV now attempts to return to the BIOS, resorting to INT 18 only
if the BIOS stack has been corrupted.

This also fixes a bug in rdtsc_currticks when the result did not fix in %eax

Signed-off-by: Alexey Zaytsev <zaytsev.a@protei.ru>

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.

Replace a printf with a DBG in timer_rtdsc.c
Replace a printf in timer.c with assert
Return proper error codes from timer drivers

Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>

Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>

	Timer subsystem initialization code in core/timer.c

	Split the BIOS and RTDSC timer drivers from i386_timer.c

	Split arch/i386/firmware/pcbios/bios.c into the RTSDC
	timer driver and arch/i386/core/nap.c

	Split the headers properly:
		include/unistd.h - delay functions to be used by the
					gPXE core and drivers.

		include/gpxe/timer.h - the fimer subsystem interface
					to be used by the timer drivers
					and currticks() to be used by
					the code gPXE subsystems.

		include/latch.h	- removed
		include/timer.h - scheduled for removal. Some driver
					are using currticks, which is
					only for core subsystems.

Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>

As written, if the if the UNDI ISR call clobbers the upper halves of
any of the GPRs (which by convention it is permitted to do, and by
paranoia should be expected to do) then nothing in the interrupt
handler will recover the state.

Additionally, save/restore %fs and %gs out of sheer paranoia - it's a
cheap enough operation, and may prevent problems due to poorly written
UNDI stacks.

Since we don't know what the UNDI code does, it is safest to
save/restore %eflags even though the lower half of %eflags is
automatically saved by the interrupt itself.

As written, if the if the UNDI ISR call clobbers the upper halves of
any of the GPRs (which by convention it is permitted to do, and by
paranoia should be expected to do) then nothing in the interrupt
handler will recover the state.

Additionally, save/restore %fs and %gs out of sheer paranoia - it's a
cheap enough operation, and may prevent problems due to poorly written
UNDI stacks.

_textdata_link_addr, _load_addr and _max_align in the linker scripts.
A bug in some versions of ld causes segfaults if the DEFINED() macro
is used in a linker script *and* the -Map option to ld is present.

We don't currently need to override any of these values; if we need to
do so in future then the solution will probably be to always specify
the values on the ld command line, and have the linker script not
define them at all.