This is a collection of Intel®’ IA32® Software Developer's Manuals (URL of the day) and AMD' AMD64 Architecture Programmer's Manual together with the related specifications, application notes, white papers, and change logs. The collection aims to keep all available revisions. It was originally created by Michal Necasek, see OS/2 Museum.

If you have a public document, related to the IA32® specifications and missing from the collection, please mail it to me. The content of this URL and all sub-ULRs is available for convenient bulk download by rsync x86docs password "" (empty).

HLT

Halting breakpoint causes a software breakpoint to occur.

Halting breakpoint is always unconditional, even inside an IT block.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

Decode for this encoding

if EDSCR().HDE == '0' || !HaltingAllowed() then Undefined(); end; if cond != '1110' then UnpredictableProcedure(); end; // HLT must be encoded with AL condition

CONSTRAINED UNPREDICTABLE behavior

If cond != '1110', then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as NOP.
• The instruction executes unconditionally.
• The instruction executes conditionally.

T1

Decode for this encoding

if EDSCR().HDE == '0' || !HaltingAllowed() then Undefined(); end;

Assembler Symbols