Date: Fri, 18 Jan 2013 06:03:32 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r245577 - in head/sys: amd64/amd64 i386/i386 x86/x86 Message-ID: <20130118040332.GT2522@kib.kiev.ua> In-Reply-To: <201301172132.r0HLWQHD004835@svn.freebsd.org> References: <201301172132.r0HLWQHD004835@svn.freebsd.org>
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--zpd1bWBxfrI+71+6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 17, 2013 at 09:32:26PM +0000, John Baldwin wrote: > Author: jhb > Date: Thu Jan 17 21:32:25 2013 > New Revision: 245577 > URL: http://svnweb.freebsd.org/changeset/base/245577 >=20 > Log: > Don't attempt to use clflush on the local APIC register window. Various > CPUs exhibit bad behavior if this is done (Intel Errata AAJ3, hangs on > Pentium-M, and trashing of the local APIC registers on a VIA C7). The > local APIC is implicitly mapped UC already via MTRRs, so the clflush is= n't > necessary anyway. > =20 > MFC after: 2 weeks I am curious, was there a case where the clflush was really executed on the LAPIC register window with the pristine HEAD code ? I think that there is no Intel processors which support clflush instruction and do not have self-snoop. On the other hand, please note that the same change could be due for the pmap_invalidate_cache_pages(). Unlike pmap_invalidate_cache_range(), _pages() uses clflush unconditionally on purpose, since it is intended for devices which do not snoop. --zpd1bWBxfrI+71+6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJQ+MmTAAoJEJDCuSvBvK1BYCgQAJq2wMsms/Y/j8FjwWynSp0n LL+4XHq6fVH8wQEr27Y2poVmqjPGb38SprQDzzA/bk7/ihF1KX8UeYYRKo4J2PvI j9wErfFOpvoLh8RmXXHsjW0rnVmENnvKv3V7ylRSfVxCSolivIoTBfOLnPaW6ZCC GT8WrDmyWWMp5BLl+6uvLkCYSpowIPRA+TGEIqJ59iKFFpoM8X+00mi6lBe1jLH6 U5g1HPcFG+s+1K5P1gfNM5FARxq30rku2pZtbhP6xoGrNbIPYoEFynJNUXYz5wsM WfubWKhmqWrIAYdgLoMAdtV3Op9847LHo8k+QX+quUHM3sQpDc7EpUAHDl37dwgN vUp3KbiYNUpPO4Y15wPfTCtSJuYB5zletPHPSRkwB5wIsqtcBLZszUkEBHX4rE64 8FyyPei5F43RWv4VphMWRX+xCrAvYMkrUb81p4q24i5drmDUmrnEzUyKmnJHPmpO 8pbcEfrkog2WdmN512jeEg/0fHl7G2PQROpK6+cgad0U1I7sIt5mqbgrfg7nY8a0 bdLQL6KCCZP2hSkyUIiQ1S+RdPemYsknnq1vEc43z5ecBXEdw++pAzXp98DhEKWv cANU7sR5cDCTrdhkxPNV74T1VsgjMGXnkp/8g2usAdSCVFvHzGZWySwRXKFi+eV8 wlsg7NGTR2D9ZtbyHz8n =PmLn -----END PGP SIGNATURE----- --zpd1bWBxfrI+71+6--
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