Re: xchg & lock question

"Eman" <spamtrap@xxxxxxxxxx> wrote:

According to Intel' manual "when a memory operand is used with
the XCHG instruction, the processor's LOCK signal is automatically
asserted". AMD documentation also states that.

Can someone tell me, which of IA32 compatible processors do not
assert LOCK automatically in the case of XCHG reg,[mem] ?

None of them. If they are IA32-compatible, then they MUST assert LOCK with
XCHG. That's one of the fundamental behaviors. Windows would break if
they didn't.
--
- Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.

.

Relevant Pages

  • Re: xchg & lock question
    ... > According to Intel' manual "when a memory operand is used with the XCHG ... the processor's LOCK signal is automatically ... > assert LOCK automatically in the case of XCHG reg,? ...
    (comp.lang.asm.x86)
  • Re: xchg & lock question
    ... assert LOCK automatically in the case of XCHG reg,? ... think *all* IA32 processors employ locking for this instruction. ...
    (alt.lang.asm)
  • Re: lock
    ... Someplace it says that lock is active only if is involved, and sometimes it says that xchg allways incurs a lock. ... is there a great deal of diffrence between running two threads on a single CPU and or many? ... The few apps I have that uses threads, act incredibly diffrent from machine to machine and os to os. ...
    (alt.lang.asm)
  • Re: Non blocking spin lock..
    ... The unconditional call to 'xchg' flushes the ... There is no need to synchronize the CPU if you definitely can't ... lock is attempted. ...
    (comp.programming.threads)
  • Re: xchg & lock question
    ... the XCHG instruction, the processor's LOCK signal is automatically ... assert LOCK automatically in the case of XCHG reg,? ... The 8088/8086/80188/80186 ref man implies they didn't. ...
    (alt.lang.asm)