[pcbios] Support arbitrary splits of the e820 memory map
Allow for an arbitrary number of splits of the system memory map via
INT 15,e820.
Features of the new map-mangling algorithm include:
Supports random access to e820 map entries.
Requires only sequential access support from the underlying e820
map, even if our caller uses random access.
Empty regions will always be stripped.
Always terminates with %ebx=0, even if the underlying map terminates
with CF=1.
Allows for an arbitrary number of hidden regions, with underlying
regions split into as many subregions as necessary.
Total size increase to achieve this is 193 bytes.
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.
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.
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>
Experimentation reveals that gcc ignores -mrtd for the implicit
arithmetic functions (e.g. __udivdi3), but not for the implicit
memcpy() and memset() functions. Mark the implicit arithmetic
functions with __attribute__((cdecl)) to compensate for this.
(Note: we cannot mark with with __cdecl, because we define __cdecl to
incorporate regparm(0) as well.)
We don't actually have a stdio.h header file. Our printf() functions are
defined in vsprintf.h. (This may change, since vsprintf.h is a
non-standard name, but for now it's the one to use.)
There should be no need to include vsprintf.h just for DBG() statements,
since include/compiler.h forces it in for a debug build anyway.