[pcbios] Don't use "lret $2" to return from an interrupt
Using "lret $2" to return from an interrupt causes interrupts to be
disabled in the calling program, since the INT instruction will have
disabled interrupts. Instead, patch CF on the stack and use iret to
return.
Interestingly, the original PC BIOS had this bug in at least one
place.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Michael Brown <mcb30@etherboot.org>
[pcbios] Add facility for testing arbitrary E820 memory maps
We seem to be having issues with various E820 memory maps. These
problems are often difficult to reproduce, requiring access to the
specific system exhibiting the problem.
Add a facility for hooking in a fake E820 map generator, using an
arbitrary map defined in a C array, solely in order to be able to test
the map-mangling code against arbitrary E820 maps.
Michael Brown