Re: Scheduler fixes for hyperthreading

From: Sam Lawrance (boris_at_brooknet.com.au)
Date: 05/22/05

  • Next message: Colin Percival: "Re: Scheduler fixes for hyperthreading" 
    To: Colin Percival <cperciva@freebsd.org>
Date: Sun, 22 May 2005 15:02:50 +1000

    On Sat, 2005-05-21 at 21:35 -0700, Colin Percival wrote:
    > Marcel Moolenaar wrote:
    > > There are a lot of variables that need to be taken into account and
    > > those variables do not necessarily map perfectly from a P4 to an I2.
    > > Sharing of the L1 cache is not a sufficient condition to create a
    > > side-channel for timing attacks. A reliable time source with enough
    > > precision is also necessary (as you and Stephan have pointed out).
    > > The precision of the time source depends on latencies of the various
    > > cache levels and the micro-architectural behavior of the processor.
    >
    > Point taken. I maintain, however, that it is much better to make
    > "information can leak between these processors" a machine-independent
    > concept which is handled appropriately by the scheduler (with the
    > necessary machine-dependent code to specify *which* sets of processors,
    > if any, have such leakage).

    I'm just curious here... would the mac_seeotheruids policy help in
    obscuring the value of any information collected by a spy process?

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