somewhat redundant, and also causes gas to complain when we include
the profiling code (which uses an i586 instruction).

reflect the fact that they allocate and deallocate user memory (i.e.
things reached through a userptr_t).

doesn't want to go to the hassle of processing a full memory map.

initrds.

Parse command line for "vga=" and "mem=" parameters

Add a path for isolinux.bin that is correct on my system; hopefully it
will work on others too.

Move pxe_boot() code to pxe_image.c

Shut down before jumping to the multiboot image.

do it.

set_fbms() will also update the E820 hidden region.

to start on a non-page boundary.  Make life safer by rounding out our
edited regions.

Add IMAGE_PXE to use the new image format framework.  "kernel pxelinux.0"
now works.

don't overwrite the parameter block until *after* the debug code.

clue what the "previous" interrupt handler will do, which could range
from "just an iret" to "disable the interrupt"), and that means that
we have to take responsibility for ACKing all interrupts.  Joy.

allocation.

if we don't.

address, to work around OS bugs.

alignment.

userptr_add().

it if we don't.

refer to them by name from the command line, or build them into a
multiboot module list.

Use setting image->type to disambiguate between "not my image" and "bad
image"; this avoids relying on specific values of the error code.