[status report #2] BHyVe BIOS emulation to boot legacy systems

[Takuya ASADA]

* project summary
The project goal is to support BIOS emulation on BHyVe, enabling boot
from disk image.
I going to focus booting FreeBSD/amd64 from disk image on this GSoC,
but final goal is to make BHyVe able to support more guest OSes.

* Implement sample pseudo-BIOS
Implemented sample pseudo-BIOS witch call VMCALL at BIOS entry address.
Implement "bhyvebiosloader" will next step for week 3.

[Makefile]
all:
	cc -m32 -c pseudobios.S -o pseudobios.o
	ld -melf_i386_fbsd -T ldscript.lds pseudobios.o -o pseudobios.elf
	objcopy -I elf32-i386-freebsd -O binary pseudobios.elf pseudobios.bin
clean:
	rm *.o *.elf *.bin

[ldscript.lds]
OUTPUT_FORMAT("elf32-i386")
OUTPUT_ARCH("i386")
SECTIONS
{
	.text 0xffff0 :
	{
		*(.text)
		*(.rodata)
	} = 0
	.data :
	{
		*(.data)
	}
	.sbss :
	{
		*(.sbss)
		*(.scommon)
	}
	.bss :
	{
		*(.bss)
		*(COMMON)
	}
}

[pseudobios.S]
	.code16gcc
	vmcall