Date: Mon, 24 Apr 2006 17:31:37 -0400 From: Jung-uk Kim <jkim@FreeBSD.org> To: Colin Percival <cperciva@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/amd64/amd64 mp_machdep.c src/sys/i386/i386 mp_machdep.c Message-ID: <200604241731.40117.jkim@FreeBSD.org> In-Reply-To: <200604242117.k3OLH2RG032117@repoman.freebsd.org> References: <200604242117.k3OLH2RG032117@repoman.freebsd.org>
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On Monday 24 April 2006 05:17 pm, Colin Percival wrote: > cperciva 2006-04-24 21:17:02 UTC > > FreeBSD src repository > > Modified files: > sys/amd64/amd64 mp_machdep.c > sys/i386/i386 mp_machdep.c > Log: > Adjust dangerous-shared-cache-detection logic from "all shared > data caches are dangerous" to "a shared L1 data cache is > dangerous". This is a compromise between paranoia and performance: > Unlike the L1 cache, nobody has publicly demonstrated a > cryptographic side channel which exploits the L2 cache -- this is > harder due to the larger size, lower bandwidth, and greater > associativity -- and prohibiting shared L2 caches turns Intel Core > Duo processors into Intel Core Solo processors. > > As before, the 'machdep.hyperthreading_allowed' sysctl will allow > even the L1 data cache to be shared. > > Discussed with: jhb, scottl > Security: See FreeBSD-SA-05:09.htt for background material. > > Revision Changes Path > 1.272 +2 -2 src/sys/amd64/amd64/mp_machdep.c > 1.265 +2 -2 src/sys/i386/i386/mp_machdep.c Cool! I was working on the same thing. :-) http://www.freebsd.org/cgi/query-pr.cgi?pr=96203 Jung-uk Kim
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