The initrd_addr_max field represents the highest byte address that may
be used to hold initrd images, and is therefore almost certainly not
aligned to a page boundary: a typical value might be 0x7fffffff.

Fix the address calculations to ensure that the initrd images are
always aligned to a page boundary.

Reported-by: Sitsofe Wheeler <sitsofe@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Some BIOSes (observed with an HP Gen9) seem to spuriously enable
interrupts at the PIC.  This causes problems with NBPs such as GRUB
which use the UNDI API (thereby enabling interrupts on the NIC)
without first hooking an interrupt service routine.  In this
situation, the interrupt will end up being handled by the default BIOS
ISR, which will typically just send an EOI and return.  Since nothing
in this handler causes the NIC to deassert the interrupt, this will
result in an interrupt storm.

Entertainingly, some BIOSes are immune to this problem because the
default ISR sends the EOI only to the slave PIC; this effectively
disables the interrupt.

Work around this problem by disabling the interrupt on the PIC before
invoking the PXE NBP.  An NBP that expects to make use of interrupts
will need to be configuring the PIC anyway, so it is probably safe to
assume that it will explicitly reenable the interrupt.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Signed-off-by: Michael Brown <mcb30@ipxe.org>

On a 64-bit CPU, any modification of a register by 32-bit or 16-bit
code will destroy the invisible upper 32 bits of the corresponding
64-bit register.  For example: a 32-bit "pushl %eax" followed by a
"popl %eax" will zero the upper half of %rax.  This differs from the
treatment of upper halves of 32-bit registers by 16-bit code: a
"pushw %ax" followed by a "popw %ax" will leave the upper 16 bits of
%eax unmodified.

Inline assembly generated using REAL_CODE() or PHYS_CODE() will
therefore have to preserve the upper halves of all registers, to avoid
clobbering registers that gcc expects to be preserved.

Output operands from REAL_CODE() and PHYS_CODE() assembly may
therefore contain undefined values in the upper 32 bits.

Fix by using explicit variable widths (e.g. uint32_t) for
non-discarded output operands, to ensure that undefined values in the
upper 32 bits of 64-bit registers are ignored.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Move most arch/i386 files to arch/x86, and adjust the contents of the
Makefiles and the include/bits/*.h headers to reflect the new
locations.

This patch makes no substantive code changes, as can be seen using a
rename-aware diff (e.g. "git show -M5").

This patch does not make the pcbios platform functional for x86_64; it
merely allows it to compile without errors.

Signed-off-by: Michael Brown <mcb30@ipxe.org>