Date: Sun, 22 May 2005 15:02:50 +1000 From: Sam Lawrance <boris@brooknet.com.au> To: Colin Percival <cperciva@freebsd.org> Cc: Marcel Moolenaar <marcel@xcllnt.net> Subject: Re: Scheduler fixes for hyperthreading Message-ID: <1116738170.867.28.camel@dirk.no.domain> In-Reply-To: <42900C01.10904@freebsd.org> References: <428FC00B.3080909@freebsd.org> <aef05e1ae6104223181ad3cf03e11390@xcllnt.net> <428FD710.4060200@freebsd.org> <9e8314b53980a379445cc8c07086901d@xcllnt.net> <428FE788.8020408@freebsd.org><42900C01.10904@freebsd.org>
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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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