Pull various network stack fixes from Gene Cumm and adapt to the 6.xx
core_udp_* API,

* 'elflink-pxe-fixes-for-mfleming-2' of git://github.com/geneC/syslinux:
  PXE ISR: Force polling on select hardware WORKAROUND
  core/lwip: Fix NULL pointer check
  PXE: use ddprintf macro
  com32: Define ddprintf() macro
  PXELINUX: specify PXE/lwIP
  undiif: show thread of execution on UNDIIF_ID_DEBUG
  core: dprintf() the banner.
  PXELINUX: Use sendto() instead of connect()/send()/disconnect()
  core: make mbox_post()/__sem_down_slow() check if valid
  core: mbox/semaphore NULL checks
  core/lwip/undi: Improve UNDIIF_ID_DEBUG messages

Conflicts:
	core/fs/pxe/pxe.c
	core/fs/pxe/tftp.c
	core/init.c

Duplicating Debug Printf;  Certain warning/error printf()
 statements are not visible if they occur before ldlinux.c32
 is loaded

Signed-off-by: Gene Cumm <gene.cumm@gmail.com>

syslinux-5.11-pre8

Conflicts:
	NEWS
	com32/lib/Makefile
	core/conio.c
	mk/devel.mk
	mk/elf.mk

It's useful to be able to enable (and disable) debug code at runtime,
particularly for allowing users that are unable to build their own
Syslinux releases the chance to provide useful debugging output.

For example, say a user reports trouble with their PXE stack but doesn't
have a development environment setup to turn on the debug code
themselves. With this change you can simply request that they do,

    debug.c32 -e pxe_call unload_pxe open_file

to enable the debug in those functions. By only turning on code in
specific functions we reduce the chance of disrupting the buggy
behaviour and improve the signal to noise ratio for print statements.

To disable debug code use the -d flag,

    debug.c32 -d pxe_call

To use this new feature simply do,

    if (syslinux_debug_enabled) {
        debug1();
        debug2();
        ....
    }

from within the function you wish to add debug code. Note that this
feature is not limited to print statements - you can put any code within
the conditional, such as verifying a checksum or checking for memory
leaks.

The plan is to leave the dynamic debug code built in for all prereleases
and to turn it off for final releases.

People may still want to build with all dprintf() statements enabled,
and so a new symbol, DYNAMIC_DEBUG, was introduced rather than
repurposing the old DEBUG, DEBUG_STDIO and DEBUG_PORT symbols.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

Use of DEBUG macro clases with gnu-efi library. This patch defines
CORE_DEBUG. Appropriate changes to sources are made as a result. Also,
the linker error on __bad_SEG is fixed.

Signed-off-by: Chandramouli Narayanan <chandramouli.narayanan@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

We really, really don't want to accidentally spew output to a debug
port in production, so make it obligatory to define DEBUG_PORT or
DEBUG_STDIO in order for the debugging code to be compiled in.  Since
DEBUG_STDIO just turns the debugging code into stdio references, we
only need to compile the code for the DEBUG_PORT case.

Add a commented-out line to mk/devel.mk to make it easier for users.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Matt Fleming <matt.fleming@intel.com>

Always define dprintf2/vdprintf2 even with no debugging at all
enabled.

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

Add the ability to redirect dprintf to stdio when there is no other
choice.

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

Resolved Conflicts:

	com32/lib/dprintf.c
	com32/lib/vdprintf.c

Fix an uninitialized pointer bug; return void rather than returning
int like normal printfs... if we're depending on the return value of a
debugging function we're screwed when debugging is disabled.

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

Actually provide real infrastructure for debug-to-serial.  Very
useful when debugging fullscreen applications, especially under an
emulator like Qemu.

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