Messages in this thread | | | From | Daniel Pittman <> | Subject | Re: i686 quirk for AMD Geode | Date | Thu, 12 Nov 2009 11:51:55 +1100 |
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"H. Peter Anvin" <hpa@zytor.com> writes: > On 11/10/2009 09:24 AM, Alan Cox wrote: >>> >>> In the short term, yes, of course. However, if we're going to do >>> emulation, we might as well do it right. >> >> Why is using KVM doing it right ? It sounds like its doing it slowly, >> and hideously memory inefficiently. You are solving an uninteresting >> general case problem when you just need two tiny fixups (or perhaps 3 if >> you want to fix up early x86-64 prefetch) > > Why do we only need "two tiny fixups"? Where do we draw the line in > terms of ISA compatibility? One could easily argue that the Right > Thing[TM] is to be able to process any optional instruction -- otherwise > one has a very difficult place to draw a line. > > Consider SSE3, for example. Why should the same concept not apply to > SSE3 instructions as to CMOV?
FWIW, the issue of the binary-only flashplayer.so came up later in the thread, but to add my few cents:
When flash 10 was released the binary only 64-bit version generated instructions from the LAHF set unconditionally, in part because Windows chose to emulate those on the very few x86-64 platforms that didn't do them in hardware.
At that time it would have been very nice from a "user support" point of view to be able to add LAHF emulation to support the software. Yes, it is ugly, binary-only code, but it is reasonably popular...
Daniel
...in the end, in fact, popular enough to have at least a couple of people I know purchase a new CPU that did implement it, just for flash on Linux. -- ✣ Daniel Pittman ✉ daniel@rimspace.net ☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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