Michael Brown
d3db00ecf9
[pcbios] Restrict external memory allocations to the low 4GB
When running the 64-bit BIOS version of iPXE, restrict external memory
allocations to the low 4GB to ensure that allocations (such as for
initrds) fall within our identity-mapped memory region, and will be
accessible to the potentially 32-bit operating system.
Move largest_memblock() back to memtop_umalloc.c, since this change
imposes a restriction that applies only to BIOS builds.
Signed-off-by: Michael Brown <mcb30@ipxe.org>