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Date: Fri, 22 May 2009 15:32:41 -0500 From: "Michael S. Zick" <lkml@...ethan.org> To: Samuel Thibault <samuel.thibault@...-lyon.org> Cc: Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org Subject: Re: [BUG FIX] Make x86_32 uni-processor Atomic ops, Atomic On Fri May 22 2009, Samuel Thibault wrote: > Michael S. Zick, le Fri 22 May 2009 14:53:39 -0500, a écrit : > > Ref: http://developer.intel.com/Assets/PDF/manual/253666.pdf > > Manual page: 3-590 PDF page: 638 > > Summary: Processors prior to P-4 can take an interrupt between > > the read cycle and the write cycle. Which is why opcode 0xF0 exists. > > Where do you see page 638/639 talking about interrupts? It talks about > multi-processor machines. > No - it talks about "exclusive memory access" - You got bus master DMA in your test machine? You also have an older than P-4 single processor? Look people, I just reported what I found from testing - Please don't shoot the messanger. If it: "Does not make a difference" then it "Should not make a difference" but it does, try it yourself. Its safe (if LOCK_PREFIX is in the proper places) - the machine will ignore the opcode if is recent enough to not need it - just trust the cpu's micro-code. Mike > Samuel > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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