Was NOP deprecated for AA64? NASM not disassembling...
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From: Alexei A. Frounze on 18 Feb 2010 17:31 On Feb 18, 12:24 pm, "Rod Pemberton" <do_not_h...(a)havenone.cmm> wrote: > If NOP was deprecated or obsoleted for AA64, I can't find it stated any the > Intel or AMD 64-bit manuals. But, it seems NDISASM is disassembling it as > an XCHG RAX,RAX with REX.W=1. (2.06rc8 and 2.08rc9) > > 00000000 90 nop > 00000001 4090 nop > 00000003 4890 xchg rax,rax > > From the manuals, 90h is a NOP instruction for any exchange of AX, EAX, RAX > with itself. Use of the new registers via a REX is an XCHG. If all 40h to > 4Fh prefixes are inserted, it's disassembling REX.W=0 with REX.R=0 as NOP, > which I believe is correct. But, it's also disassembling REX.W=1 with > REX.R=0 as XCHG RAX,RAX which I currently believe is incorrect and should be > NOP, at least according to both sets of manuals, AFAICT. > > Comments? > > Rod Pemberton AFAIR, unless it's XCHG rAX, r8, it's NOP. Alex
From: James Harris on 18 Feb 2010 19:34 On 18 Feb, 20:24, "Rod Pemberton" <do_not_h...(a)havenone.cmm> wrote: > If NOP was deprecated or obsoleted for AA64... AA64? Another term for Amd64 or x86-64? Surely another term is not needed - though feel free to ditch Intel's term for it! James
From: BGB / cr88192 on 18 Feb 2010 20:24 "James Harris" <james.harris.1(a)googlemail.com> wrote in message news:cbac287f-b456-4336-b36a-0929252ae289(a)b2g2000yqi.googlegroups.com... > On 18 Feb, 20:24, "Rod Pemberton" <do_not_h...(a)havenone.cmm> wrote: >> If NOP was deprecated or obsoleted for AA64... > > AA64? Another term for Amd64 or x86-64? Surely another term is not > needed - though feel free to ditch Intel's term for it! > hmm, I did my own x86 interpreter and it also half-assedly supports x86-64... maybe I can rebrand it as "BGBEX64T+"... and, maybe "VIA64XTREME" if referring to a VIA implementation. ok, not really... yeah, personally I prefer to call it either x86-64 or x64, although more often using x86-64 for the architecture in general, and x64 when the context is more narrow (usually, how the x86-64 ISA is typically used within the context of Win64, which is where the term x64 is most often used, or for arch-specific function or file names, ...). > James
From: Rod Pemberton on 19 Feb 2010 03:55
"James Harris" <james.harris.1(a)googlemail.com> wrote in message news:cbac287f-b456-4336-b36a-0929252ae289(a)b2g2000yqi.googlegroups.com... > On 18 Feb, 20:24, "Rod Pemberton" <do_not_h...(a)havenone.cmm> wrote: > > If NOP was deprecated or obsoleted for AA64... > > AA64? Another term for Amd64 or x86-64? Surely another term is not > needed - though feel free to ditch Intel's term for it! > It's good enough for Sandpile.org... Other than the Intel/AMD manuals, is there an x86 source more respected than Christian Ludloff's Sandpile.org? http://www.sandpile.org/ x86 and x86-64 are the primary names on the front page, but IA-32 and AA-64 are on the architecture pages. Rod Pemberton |