[lkml]   [2011]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [GIT PULL] omap changes for v2.6.39 merge window
    On Mon, 2011-04-04 at 14:31 +0100, Russell King - ARM Linux wrote:
    > On Mon, Apr 04, 2011 at 02:24:17PM +0100, Marc Zyngier wrote:
    > > On Mon, 2011-04-04 at 12:21 +0100, Russell King - ARM Linux wrote:
    > > > Whether its worth it or not is questionable - the above is more lines
    > > > of code than many of the existing implementations, and we're not going
    > > > to shrink the existing implementations by much (maybe one to three
    > > > lines.) The only thing we gain is the ability to select an implementation
    > > > at runtime.
    > >
    > > I believe this last point to be rather important if we plan to have this
    > > mythical single kernel covering several architectures. It's also nice
    > > for the A15 to be able to use some default sched_clock() implementation
    > > as a fallback if the generic timers are not available for some reason.
    > If ARM are going to architect a set of timers into the hardware, let's
    > make sure that all such hardware has them so we can dig ourselves out
    > of this crappy mess that we find ourselves in today.

    As far as I know, A15 always has a set of generic timers.

    It may be that they are not available (frequency not programmed into the
    CNTFREQ register), or that someone decided to use a better alternative
    (for some particular interpretation of "better").

    Overall, it seems like we need some degree of flexibility to have
    several sched_clock() implementations within a single image, whether it
    is to support multiple platforms, or to allow a single architecture to
    pick the best alternative given a set of initial conditions.

    Reality is an implementation detail.

     \ /
      Last update: 2011-04-04 15:59    [W:0.020 / U:47.208 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site