[syslinux] debugging pxelinux

[Patrick Welche]

I have reason to believe that an odd box that is having boot trouble has
three instances of "!PXE" in the chunk of memory that "Method D" should
look at.

I thought I would try to find out how pxelinux copes with this, by trying
to insert printfs in pxe_init, but nothing gets printed.

I can spew lots of output if I set

	DEBUGOPT = -DDEBUG=1 -DDEBUG_STDIO -DCORE_DEBUG=1

but given that this box doesn't have a serial port, anything I add will
whizz off the screen.

>From looking at com32/include/dprintf.h, it looks as though all this does is
to define dprintf to printf, so why is it that if don't define DEBUG_STDIO
and CORE_DEBUG, and just use printf directly, nothing appears?

I assume (given the dprintfs) that ldlinux.c32 is loaded by the time
pxe_init is run, so printf calls should be legal.

What am I missing?

Cheers,

Patrick