topic Re: protected mode initialization in Software Archive

protected mode initialization

mike931201 — Mon, 20 Nov 2006 14:34:34 GMT

I'm trying to compile the protected mode initialization example from
the Intel Software Developer's Manual Volume 3A using MASM, but I'm
getting some errors I don't know how to fix.

I put the code at:

http://www.coolgroups.com/asm/pm5.asm

If anyone has tips on how to get it working, I'd appreciate it.

Re: protected mode initialization

Intel_Software_Netw1 — Tue, 21 Nov 2006 08:58:34 GMT

Hi Mike,

What errors are you receiving?

(for those following along, the developer manuals are here: http://developer.intel.com/products/processor/manuals/index.htm)

Lexi S.

IntelSoftware NetworkSupport

http://www.intel.com/software

Re: protected mode initialization

mike931201 — Tue, 05 Dec 2006 00:33:25 GMT

MASM doesn't seem to recognize the LGDT instruction.

Re: protected mode initialization

Intel_Software_Netw1 — Tue, 05 Dec 2006 08:23:49 GMT

One member of our engineering team suggests that youtry adding this macro toyour file:

LGDT macro mem:req

local x,y

x:

prefetchnt1 mem

y:

org x

byte 0fh

byte 01h

org y

endm

Another member of our engineering team responded as follows:

As of MSVC 2005 in both the 32-bit ml.exe and 64-bit cross-tools ml64.exe, the followingworks just fine when using LGDT... key is to use "FWORD PTR" as operand size modifier and when doing this in 32-bit code, also include ".686P" assembler pseudo-op to enable privileged instructions. Results in same opcode, i.e. 0F 01, being emitted in both 64-bit mode and compatibility/legacy mode. Also, please make sure that section 9.8 of Intel 64 and IA-3 2 Architectures Software Developer's Manual Volume 3A: System Programming Guide and related sections are well understood, as there are implications in order in which steps must be done when altering protected mode operation.

Lexi S.

IntelSoftware NetworkSupport

http://www.intel.com/software