Messages in this thread | | | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [PATCH RFC] x86: fix confusing name of /proc/cpuinfo "ht" flag | Date | Fri, 13 Nov 2009 11:24:23 +0100 |
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On Friday 13 November 2009 08:42:48 Ingo Molnar wrote: > > * H. Peter Anvin <hpa@zytor.com> wrote: > > > On 11/12/2009 10:37 AM, Dave Jones wrote: > > > On Thu, Nov 12, 2009 at 06:59:08PM +0100, Ingo Molnar wrote: > > > > > It's an ABI. Keep it stable, please. > > > > > > > > That's generally true, but i'm not suggesting that: i'm suggesting to > > > > _clear_ the HT flag from the cpufeatures if there's only one sibling. > > > > It's meaningless in that case and as the link quoted by the original > > > > patch shows many people are confused by that. > > > > > > > > I have such a box so i can test it. (but i dont expect any problems) > > > > > > I agree that it's an ABI change, but any software depending on its current > > > state has to implement a fallback for the case where 'ht' isn't present anyway > > > unless there's some program that only runs on ht capable hardware, which > > > sounds just crazy. > > > > > > The only potential for breakage that I can see is that code that is tuned > > > to be run in the HT case will stop running in cases where it shouldn't. > > > Which sounds like a positive thing to me. > > > > The most likely breakage would be some stupid licensing scheme. > > > > The other aspect is that we as much as possible have tried to stay to > > the hardware-documented names of these strings. Inventing new strings > > is generally a bad idea. > > Agreed - and we rejected such patches a couple of times in the past and > for good reasons. Some /proc details are rarely used by apps (so they > are no real ABIs) but cpuinfo is frequently parsed. > > Clearing the ht flag on non-hyperthreading CPUs would be a limited > quirk/fix in essence applicable to a relatively narrow range of CPUs - > and easily undone, should it cause any problems. So if Bart wants to > take a stab at that it would be a nice solution to the problem at hand > ...
I'm rather busy with other/real stuff so if anybody wants to beat me to making the proper quirk just feel free to do it.
-- Bartlomiej Zolnierkiewicz
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