assembly - How come `0F 1A /r` and `0F 1B /r` have been NOP before Intel MPX? -

-

on processors don't support intel mpx documentation says mpx instructions nop. namely, i've looked through these instructions, appear 0f 1a /r or 0f 1b /r unprefixed or prefixed f3, f2 or 66 bytes, depending on instruction. also, there statements bndmk:

the reg-reg form of instruction retains legacy behavior (nop).

i've tried search these opcodes in pdf (namely search string 0f 1), found there description of mpx instructions. looking in instruction set reference february 2014, i've found lots of instructions of form, not nops, e.g. f2 0f 12 /r movddup. , looking 0f 1a , 0f 1b failed find there.

looking nop found multibyte nop 0f 1f /0, doesn't coincide mpx instructions form.

so question is, documented legacy behavior of 0f 1a /r , 0f 1b /r nop? general rule form of instructions, or maybe represent non-nop instruction in nop form (like 90 standing xchg eax,eax)?

the intel pdfs have lying around indeed don't list nop either, block 0f 19-1e empty in opcode table a-3. two-byte opcode map: 08h -- 7fh (first byte 0fh). footnote says all blanks in opcode maps reserved , must not used. not depend on operation of undefined or reserved locations.

i have amd pdf 24594--rev. 3.19--september 2012, , list aforementioned block being nop in opcode table a-4. secondary opcode map (two-byte opcodes), low nibble 8­-fh. however, page actual nop instruction lists 0f 1f.


Comments

Post a Comment

Popular posts from this blog

Java 3D LWJGL collision -

-
i making 3d java game lwjgl library, , wondering how add collision detection, player not go through models. i using obj models. here objloader class, loads models: package renderengine; import java.io.bufferedreader; import java.io.file; import java.io.filenotfoundexception; import java.io.filereader; import java.util.arraylist; import java.util.list; import models.rawmodel; import org.lwjgl.util.vector.vector2f; import org.lwjgl.util.vector.vector3f; public class objloader { public static rawmodel loadobjmodel(string filename, loader loader){ filereader fr = null; try { fr = new filereader(new file("res/"+filename+".obj")); } catch (filenotfoundexception e) { system.err.println("couldn't load file!"); e.printstacktrace(); } bufferedreader reader = new bufferedreader(fr); string line; list<vector3f> vertices = new arraylist<vector3f...
Read more

spring - SubProtocolWebSocketHandler - No handlers -

-
i have ugly error during deploying spring app on jboss. 18:11:16,025 error [org.apache.catalina.core.containerbase.[jboss.web].[default-host].[/consumer]] (msc service thread 1-7) exception sending context initialized event listener instance of class org.springframework.web.context.contextloaderlistener: org.springframework.context.applicationcontextexception: failed start bean 'subprotocolwebsockethandler'; nested exception java.lang.illegalargumentexception: no handlers @ org.springframework.context.support.defaultlifecycleprocessor.dostart(defaultlifecycleprocessor.java:176) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.springframework.context.support.defaultlifecycleprocessor.access$200(defaultlifecycleprocessor.java:51) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.springframework.context.support.defaultlifecycleprocessor$lifecyclegroup.start(defaultlifecycleprocessor.java:346) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.s...
Read more

methods - python can't use function in submodule -

-
my folder structure this: pythonstuff/ program.py modulea/ __init__.py foo.py bar.py here's code bar.py : def hello(): print("hello, world!") here's code program.py : #!/usr/bin/env python3 modulea import bar bar.hello() i run $ python3 program.py somehow error: file "program.py", line 3, in <module> bar.hello() attributeerror: 'module' object has no attribute 'hello' edit: __init__.py file empty. edit2: after trying realized had bar.py in root directory contained hello() method. bar.py in modulea/ directory empty. add it import os __all__ = [] module in os.listdir(os.path.dirname(__file__)): if module != '__init__.py' , module[-3:] == '.py': __all__.append(module[:-3]) the init .py files required make python treat directories containing packages; done prevent directories common name, such string, unintentionally hiding v...
Read more