Various combinations of options 43.6, 43.7 and 43.8 dictate which
servers we send Boot Server Discovery requests to, and which servers
we should accept responses from.  Obey these options, and remove the
explicit specification of a single Boot Server from start_pxebs() and
dependent functions.

Option 43.6 can direct us to skip PXE boot server discovery and just
perform a standard DHCP filename boot.

fetch_ipv4_setting() will zero its IPv4 address argument if no such
setting exists, rather than leaving it untouched.

There are many functions that take ownership of the I/O buffer they
are passed as a parameter.  The caller should not retain a pointer to
the I/O buffer.  Use iob_disown() to automatically nullify the
caller's pointer, e.g.:

    xfer_deliver_iob ( xfer, iob_disown ( iobuf ) );

This will ensure that iobuf is set to NULL for any code after the call
to xfer_deliver_iob().

iob_disown() is currently used only in places where it simplifies the
code, by avoiding an extra line explicitly setting the I/O buffer
pointer to NULL.  It should ideally be used with each call to any
function that takes ownership of an I/O buffer.  (The SSA
optimisations will ensure that use of iob_disown() gets optimised away
in cases where the caller makes no further use of the I/O buffer
pointer anyway.)

If gcc ever introduces an __attribute__((free)), indicating that use
of a function argument after a function call should generate a
warning, then we should use this to identify all applicable function
call sites, and add iob_disown() as necessary.

A TFTP DATA packet with a block number of zero (representing a
negative offset within the file) could potentially cause problems.
Fixed by explicitly rejecting such packets.

Identified by Stefan Hajnoczi <stefanha@gmail.com>.

The DHCP client code now implements only the mechanism of the DHCP and
PXE Boot Server protocols.  Boot Server Discovery can be initiated
manually using the "pxebs" command.  The menuing code is separated out
into a user-level function on a par with boot_root_path(), and is
entered in preference to a normal filename boot if the DHCP vendor
class is "PXEClient" and the PXE boot menu option exists.

Automatically unregister any settings with the same name (and position
within the settings tree) as a newly registered settings block.

This functionality is generalised out from dhcp.c.

Some targets send a spurious CHECK CONDITION message in response to
the first SCSI command.  We issue (and ignore the status of) an
arbitary harmless SCSI command (a READ CAPACITY (10)) in order to draw
out this response.

The Solaris Comstar target seems to send more than one spurious CHECK
CONDITION response.  Attempt up to SCSI_MAX_DUMMY_READ_CAP dummy READ
CAPACITY (10) commands before assuming that error responses are
meaningful.

Problem reported by Kristof Van Doorsselaere <kvandoor@aserver.com>
and Shiva Shankar <802.11e@gmail.com>.

This really ought to be handled via monojob.c and the usual Ctrl-C
mechanism that handles cancelling DHCP or file downloads.

Try to qualify relative names in the DNS resolver using the DHCP Domain
Name.  For example:

  DHCP Domain Name: etherboot.org
  (Relative) Name: www

yields:

  www.etherboot.org

Only names with no dots ('.') will be modified.  A name with one or more
dots is unchanged.

pxe_tftp.c assumes that the first seek on its data-transfer interface
represents the block size.  Apart from being an ugly hack, this will
also screw up file size calculation for files smaller than one block.

The proper solution would be to extend the data-transfer interface to
support the reporting of stat()-like data.  This is not going to
happen until the cost of adding interface methods is reduced (a fix I
have planned since June 2008).

In the meantime, abuse the xfer_window() method to return the block
size, since it is not being used for anything else and is vaguely
justifiable.

Astonishingly, having returned the incorrect TFTP blocksize via
PXENV_TFTP_OPEN for almost a year seems not to have affected any of
the test cases run during that time; this bug was found only when
someone tried running the heavily-patched version of pxegrub found in
OpenSolaris.

PXE dictates a mechanism for boot menuing, involving prompting the
user with a variable message, waiting for a predefined keypress,
displaying a boot menu, and waiting for a selection.

This breaks the currently desirable abstraction that DHCP is a process
that can happen in the background without any user interaction.

F8 is represented by the ANSI escape sequence "^[[19~", which is not
representable as a KEY_xxx constant using the current encoding scheme.
Adapt the encoding scheme to allow F8 to be represented, since PXE
requires that we may need to prompt the user to press F8.

Remove the lazy assumption that ProxyDHCP == "DHCP with option 60 set
to PXEClient", and explicitly separate the notion of ProxyDHCP from
the notion of packets containing PXE options.

It is possible to configure a DHCP server to hand out PXE options
without a ProxyDHCP server present.  This requires setting option 60
to "PXEClient", which will cause gPXE to attempt ProxyDHCP.

We assume in several places that dhcp->proxydhcpack is set to the
DHCPACK packet containing option 60 set to "PXEClient".  When we
transition into ProxyDHCPREQUEST, set dhcp->proxydhcpack=dhcp->dhcpack
so that this assumption holds true.

We ought to rename several references to "proxydhcp" to something more
accurate, such as "pxedhcp".  Treating a single DHCP response as
potentially both DHCPOFFER and ProxyDHCPOFFER does make the code
smaller, but the variable names get confusing.

Pick out the first boot menu item from the boot menu (option 43.9) and
pass it to the boot server as the boot menu item (option 43.71).

Also improve DHCP debug messages to include more details of the
packets being transmitted.

Apparently this can cause a major speedup on some iSCSI targets, which
will otherwise wait for a timer to expire before responding.  It
doesn't seem to hurt other simple TCP test cases (e.g. HTTP
downloads).

Problem and solution identified by Shiva Shankar <802.11e@gmail.com>

Some PXE configurations require us to perform a third DHCP transaction
(in addition to the real DHCP transaction and the ProxyDHCP
transaction) in order to retrieve information from a "Boot Server".

This is an experimental implementation, since the actual behaviour is
not well specified in the PXE spec.

When sending to a multicast address, it may be necessary to specify
the source address explicitly, since the multicast destination address
does not provide enough information to deduce the source address via
the miniroute table.

Allow the source address specified via the data-xfer metadata to be
passed down through the TCP/IP stack to the IPv4 layer, which can use
it as a default source address.

eth_mc_hash() was missing a return within a switch statement, and so
always falling through to the default case and returning failure.

Move all the DHCP state transition logic into a single function
dhcp_next_state().  This will make it easier to add support for PXE
Boot Servers, since it abstracts away the difference between "mark
DHCP as complete" and "transition to boot server discovery".

The Linux PXE server (http://www.kano.org.uk/projects/pxe) does not
set the server identifier in its ProxyDHCP responses.  If the server
ID is missing, do not treat this as an error.

This resolves the "vague and unsettling memory" mentioned in commit
fdb8481d ("[dhcp] Verify server identifier on ProxyDHCPACKs").

Note that we already accept ProxyDHCPOFFERs without a server
identifier; they get treated as potential BOOTP packets.

At some point, it seems that someone decided to change the GUID for
the EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL.  Current EFI builds
ignore the older GUID, older EFI builds ignore the newer GUID, so we
have to expose both.

This allegedly optional interface seems to be compulsory if you want
EFI's PXE code to bother trying to use your network interface.

Include a minimal component name protocol so that the driver name
shows up as something other than "<UNKNOWN>" in the driver list, and a
device path protocol so that the network interface shows up as a
separate device in the device list, rather than being attached
directly to the PCI device.

Incidentally, the EFI component name protocol reaches new depths for
signal-to-noise ratio in program code.  A typical instance within the
EFI development kit will use an additional 300 lines of code to
provide slightly less functionality than GNU gettext achieves with
three additional characters.

The UEFI specification does not mention ROM checksums, and reassigns
the field typically used as a checksum byte.  The UEFI shell
"loadpcirom" utility does not verify ROM checksums, but it seems that
some UEFI BIOSes do.

Some devices take a very long time to initialise.  This can make it
difficult to visually distinguish between the error cases of failing
to start executing C code and failing to initialise a device.

Add a "gPXE initialising devices..." message.  The trailing ellipsis
indicates to the user that this may take some time, and the presence
of the message indicates to the developer that relocation etc. all
succeeded.

Merge in the changes that allow for building EFI driver images (that
can be loaded using the EFI shell's "load" command) as well as EFI
applications.

elf2efi converts a suitable ELF executable (containing relocation
information, and with appropriate virtual addresses) into an EFI
executable.  It is less tightly coupled with the gPXE build process
and, in particular, does not require the use of a hand-crafted PE
image header in efiprefix.S.

elf2efi correctly handles .bss sections, which significantly reduces
the size of the gPXE EFI executable.

Conventional usage of the various struct sockaddr_xxx types involves
liberal use of casting, which tends to trigger strict-aliasing
warnings from gcc.  Avoid these now and in future by marking all the
relevant types with __attribute__((may_alias)).

The check for unresolved symbols does not explicitly specify an output
architecture format, and so causes a warning when building an i386 EFI
binary on an x86_64 platform.  This warning is harmless, and
specifying the output architecture in multiple places is cumbersome,
so just inhibit the warning.

Defer the call to ib_open() until we want to actually open the device,
rather than when the device is registered.

At POST time some BIOSes return invalid e820 maps even though
they indicate that the data is valid.  We add a check that the first
region returned by e820 is RAM type and declare the map to be invalid
if it is not.

This extends the sanity checks from 8b20e5d ("[pcbios] Sanity-check
the INT15,e820 and INT15,e801 memory maps").

Driver was storing the result of pci_bar_start() and pci_bar_size() in
an int, rather than an unsigned long.

(Bug was introduced in the vendor's tree in commit eac85cd "Port
etherfabric driver to net_device api".)

adjust_pci_device() has historically enabled bus-mastering and I/O
cycles, but has never previously needed to enable memory cycles.  Some
EFI systems seem not to enable memory cycles by default, so add that
to the list of PCI command register bits that we force on.

When compiling for the Linux kernel, PCI_BASE_ADDRESS_0 == 0, and
PCI_BASE_ADDRESS_1 == 1.  This is not so when compiling for gPXE.  We
must use the symbolic names rather than integers to get the correct
values.

Bug identified and patch supplied by:

   George Chou <george.chou@advantech.com>

Currently the only supported platform for x86_64 is EFI.

Building an EFI64 gPXE requires a version of gcc that supports
__attribute__((ms_abi)).  This currently means a development build of
gcc; the feature should be present when gcc 4.4 is released.

In the meantime; you can grab a suitable gcc tree from

  git://git.etherboot.org/scm/people/mcb30/gcc/.git

The patch file supplied for commit 3a799e9 ("[hermon] Add PCI ID for
ConnectX QDR card") accidentally marked drivers/infiniband/hermon.c as
being executable.

EFI provides a copy of the SMBIOS table accessible via the EFI system
table, which we should use instead of manually scanning through the
F000:0000 segment.

EFI passes in copies of SMBIOS and other system configuration tables
via the EFI system table.  Allow configuration tables to be requested
using a mechanism similar to the current method for requesting EFI
protocols.

Patch provided by Itay Gazit <itaygazit@gmail.com>.

On non-BBS systems, we have to hook INT 19 in order to be able to boot
from the gPXE ROM at all.  However, doing this unconditionally will
prevent the user from booting via any other devices.

Previously, the INT 19 entry point would prompt the user to press B in
order to boot from gPXE, which makes it impossible to perform an
unattended network boot.  We now prompt the user to press N to skip
booting from gPXE, which allows for unattended operation.

This should be a better match for most real-world scenarios.  Most
modern systems support BBS and so are unaffected by this change.  Very
old (non-BBS) systems tend not to have PXE ROMs by default anyway; if
the user has added a gPXE ROM then they probably do want to boot from
the network.  Newer non-BBS systems are essentially limited to IBM
servers, which will recapture the INT 19 vector anyway and implement
their own boot-ordering selection mechanism.