RFC: Adding a hw.features[2] sysctl

Igor Mozolevsky igor at hybrid-lab.co.uk
Sun Jan 13 18:15:51 PST 2008


On 14/01/2008, Igor Mozolevsky <igor at hybrid-lab.co.uk> wrote:
> On 14/01/2008, Nathan Lay <nslay at comcast.net> wrote:
> > Igor Mozolevsky wrote:
> > > On 13/01/2008, Peter Jeremy <peterjeremy at optushome.com.au> wrote:
> > >
> > >
> > >> IMHO, no.  Virtually all similar FreeBSD information is exported via
> > >> sysctl and this sort of information fits neatly into the existing
> > >> MIB tree as either dev.cpu.N.features or hw.cpu.features
> > >>
> > >
> > > /dev/sndstat?
> > >
> > > If it's in /dev you can do neat tricks like ioctl-ing queries (like
> > > ioctl(/dev/cpuinfo, CINFOCTL_HAS_FEATURES, CINFO_SSE3|CINFO_SSSE3))
> > > instead of having *every* app parse the result of a sysctl; most of
> > > the time you'd only want to check for specific feature , it's much
> > > easier to do an ioctl that returns a boolean.
> >
> > Or perhaps, create an ioctl that returns a bitmask of all available CPU
> > features.  This way, only one ioctl() call is necessary and allows
> > programs to query any and all features in an inexpensive way.  Calling
> > ioctl() for each feature query is comparably more expensive.
>
> You won't you'd OR all of the features you want to check; but yes,
> having a param that returns the whole lot would also be great, as well
> as the driver returning human-readable representation if it was open
> for writing...

... for reading... It's getting late here!..


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