Messages in this thread | | | Date | Mon, 8 Sep 2008 09:07:41 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [BUG] x86 kenel won't boot under Virtual PC |
| |
On Mon, 8 Sep 2008, H. Peter Anvin wrote: > > The help text is indeed out of date. I did a patch yesterday to, among other > things, update it; I also want to verify that we are disabling all options > that can cause gcc or binutils to generate nopl's; I plan to push it today.
Peter.
The help text may be out of date because of changes to NOPL usage, but you should ask yourself whether the change is actually a _good_ change.
IOW, I really don't see why you are pushing changing the help-text, instead of just making the kernel work better.
The fact that some broken gcc/binutils versions may screw us over _anyway_ may well mean that we should just push back on _that_ change instead.
Quite frankly, from a user perspective, even a very _technical_ one, please tell me what the advantage of not being fairly generic by default is. Really.
Yes, there are some _big_ ISA issues where it is worth doing real static code selection (as opposed to just instruction selection and scheduling etc that still _works_ for everybody, but optimizes for certain archtiectures).
So things like cmpxchg/xadd (for atomics) and cmov (for compiler-generated code), and bswap (for networking) can really make a big difference, and are not really realistic to do dynamically.
But NOPL? That's simply not _worth_ it being painful over.
And the fact is, the current help text describes
(a) the historical meaning (optimize for a specific architecture, but don't make extreme choices that are bad for others) (b) what people would generally _want_.
and I really don't think that changing the help text is the right solution here. It may be "technically correct", but it is simply not user-friendly or smart.
Linus
| |