This commit implements GDB over UDP.  Using UDP is more complex than
serial and has required some restructuring.

The GDB stub is now built using one or both of GDBSERIAL and GDBUDP
config.h options.

To enter the debugger, execute the gPXE shell command:
gdbstub <transport> [<options>...]

Where <transport> is "serial" or "udp".  For "udp", the name of a
configured network device is required:
gdbstub udp net0

The GDB stub listens on UDP port 43770 by default.

Allow for timers to be started with fixed timeouts.

Tested against the mini-slamd server located in contrib/mini-slamd
with a single client, on a lossy network.

UDP sockets can be used for multicast, at which point it becomes
plausible that we could receive packets that aren't destined for us
but that still match on a port number.

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.

Return the most appropriate of EACCES, EPERM, ENODEV, ENOTSUP, EIO or
EINVAL depending on the exact error returned by the target, rather than
just always returning EPERM.

Also, ensure that error strings exist for these errors.

Various specification documents disagree about the byte ordering of
UUIDs.  However, SMBIOS seems to use the standard in which everything is
in network-endian order.

This doesn't affect anything sent on the wire; only what gets printed on
the screen when the "uuid" variable is displayed.

Drivers are not allowed to call printf().  Converted eprintf() to DBG(),
and removed spurious startup banner.

Fixed hardcoded inclusion of little_bswap.h

Use EIO rather than 1 as an error number.

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.

Infiniband devices no longer block waiting for link-up in
register_ibdev().

Hermon driver needs to create an event queue and poll for link-up events.

Infiniband core needs to reread MAD parameters when link state changes.

IPoIB needs to cope with Infiniband link parameters being only partially
available at probe and open time.

03-19-2008, Hilko Bengen, Cleanups and fixes for newer cards
(successfully tested with 8110SC-d onboard NIC)

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

The PXE spec is (as usual) unclear on precisely when ProxyDHCPREQUESTs
should be issued.  We adapt the following, slightly paranoid approach:

  If an offer contains an IP address, then it is a normal DHCPOFFER.

  If an offer contains an option #60 "PXEClient", then it is a
  ProxyDHCPOFFER.  Note that the same packet can be both a normal
  DHCPOFFER and a ProxyDHCPOFFER.

  After receiving the normal DHCPACK, if we have received a
  ProxyDHCPOFFER, we unicast a ProxyDHCPREQUEST back to the ProxyDHCP
  server on port 4011.  If we time out waiting for a ProxyDHCPACK, we
  treat this as a non-fatal error.

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.

Convert DHCP option applicators in dns.c and iscsi.c to settings
applicators.

Kill off DHCP option applicators.

Add a configuration settings block for each net device.  This will
provide the parent scope for settings applicable only to that network
device (e.g. non-volatile options stored on the NIC, options obtained via
DHCP, etc.).

Expose the MAC address as a setting.

Add the notion of the settings hierarchy, complete with
register/unregister routines.

Rename set->store and get->fetch to avoid naming conflicts with get/put
as used in reference counting.

Add the concept of an abstract configuration setting, comprising a (DHCP)
tag value and an associated byte sequence.

Add the concept of a settings namespace.

Add functions for extracting string, IPv4 address, and signed and
unsigned integer values from configuration settings (analogous to
dhcp_snprintf(), dhcp_ipv4_option(), etc.).

Update functions for parsing and formatting named/typed options to work
with new settings API.

Update NVO commands and config UI to use new settings API.

Timers are sometimes required before the call to initialise(), so we
cannot rely on initialise() to set up the timers before use.

Also fix a potential integer overflow issue in generic_currticks_udelay()

Add missing comments to timer code.

Lock system if no suitable timer source is found.

Fix initialisation order so that timers are initialised before code that
needs to use them.

show_setting() and related functions now return an "actual length" in the
style of snprintf().  This is to allow consumers to allocate buffers large
enough to hold the formatted setting.

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>

Arbel and Hermon cards both have multiple ports.  Add the
infrastructure required to register each port as a separate IB
device.  Don't yet register more than one port, since registration
will currently fail unless a valid link is detected.

Use ib_*_{set,get}_{drv,owner}data wrappers to access driver- and
owner-private data on Infiniband structures.

Pull out common code for handling management datagrams from arbel.c
and hermon.c into infiniband.c.

Add port number to struct ib_device.

Add open(), close() and mad() methods to struct ib_device_operations.

separate xfer method.

Add missing .alloc_iob entries to several xfer_interface_operations
structures.

also avoid waiting for ProxyDHCP offers).

Also reduce the ProxyDHCP timeout, because it's already irritating me.