Date: Fri, 3 Jan 2014 20:21:59 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Ian Lepore <ian@FreeBSD.org> Cc: Zbigniew Bodek <zbb@FreeBSD.org>, svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r260165 - head/sys/dev/ahci Message-ID: <20140103182159.GR59496@kib.kiev.ua> In-Reply-To: <1388767752.1158.264.camel@revolution.hippie.lan> References: <201401012026.s01KQ8KU017949@svn.freebsd.org> <20140101203212.GF59496@kib.kiev.ua> <1388767752.1158.264.camel@revolution.hippie.lan>
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--Gx6yhVhPSPzNJpj4 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 03, 2014 at 09:49:12AM -0700, Ian Lepore wrote: > On Wed, 2014-01-01 at 22:32 +0200, Konstantin Belousov wrote: > > On Wed, Jan 01, 2014 at 08:26:08PM +0000, Zbigniew Bodek wrote: > > > Author: zbb > > > Date: Wed Jan 1 20:26:08 2014 > > > New Revision: 260165 > > > URL: http://svnweb.freebsd.org/changeset/base/260165 > > >=20 > > > Log: > > > Use only mapped BIOs on ARM > > > =20 > > > Using unmapped BIOs causes failure inside bus_dmamap_sync, since > > > this function requires valid MVA address, which is not present > > > if mapping is not set up. > > > =20 > > > Submitted by: Wojciech Macek <wma@semihalf.com> > > > Obtained from: Semihalf > > >=20 > > > Modified: > > > head/sys/dev/ahci/ahci.c > > >=20 > > > Modified: head/sys/dev/ahci/ahci.c > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > > > --- head/sys/dev/ahci/ahci.c Wed Jan 1 20:22:29 2014 (r260164) > > > +++ head/sys/dev/ahci/ahci.c Wed Jan 1 20:26:08 2014 (r260165) > > > @@ -3066,7 +3066,15 @@ ahciaction(struct cam_sim *sim, union cc > > > if (ch->caps & AHCI_CAP_SPM) > > > cpi->hba_inquiry |=3D PI_SATAPM; > > > cpi->target_sprt =3D 0; > > > +#ifdef __arm__ > > > + /* > > > + * Do not use unmapped buffers on ARM. Doing so will cause > > > + * failure inside bus_dmamap_sync due to lack of VA. > > > + */ > > > + cpi->hba_misc =3D PIM_SEQSCAN; > > > +#else > > > cpi->hba_misc =3D PIM_SEQSCAN | PIM_UNMAPPED; > > > +#endif > > > cpi->hba_eng_cnt =3D 0; > > > if (ch->caps & AHCI_CAP_SPM) > > > cpi->max_target =3D 15; > >=20 > > I think this is wrong. If bus_dmamap_sync(9) is not functional on arm, > > then unmapped io should be disabled on arm unconditionally, using > > unmapped_buf_allowed. Why ahci(4) is special in this regard, leaving > > other controllers broken for arm ? >=20 > I think this entire concept is wrong, and the fix should be in armv6 > busdma or pmap code. An unmapped page is, by definition, not cached. > The only way data becomes cached is because flags in a mapping indicated > the memory is cacheable. If we have data from unmapped pages in the > cache, that's a bug in the armv6 pmap implementation, I think. I agree with the statement that the fix must be in busdma MD code, possibly with some cooperation with pmap code. On the other hand, I do not understand later claims. BIO unmapped attribute only means that bio does not carry a pointer to (some) mapping of the bio_ma pages. In other words, unmapped BIO does not imply globally unmapped page, and CPU cache might contain the lines =66rom the BIO pages. --Gx6yhVhPSPzNJpj4 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iQIcBAEBAgAGBQJSxv/GAAoJEJDCuSvBvK1B/5IP/iFASxDOpbhjCFFO21MHpQQb vlYSX7I0bBE1uxIXu4HuHg9ZH9jFSn0qhvF72Nk7gy+AriN82IxWwzFSV+G7G7ia gWwnAeeKTaoQPvpAZRRbF0GaVVN1npoBDi8f8YVn2yhI2dxGTsb5CyVyUH5vFKUq BBZ201MrUjzc+9N9ziR7etQHCkph5W4Fs5itA+It5sSWv/+K052GHjHemzodglN8 LOXVVZqw78o+0Iig2g157EUmfrfnwOMIvwVqeNAIvu4bISF+zCO24GMRqy+w2oFd lIm3mdOhBhgGJiFt+mtq/8GdQaiYIiExsztgFJrViK8VuYEU8q0tkYw+zr7NnEu9 aD3gJmVeL5boz6k4cLJJWBFJCCsHuArf9yk1jwdusP4v8A+TW6qeIgNWU2JcfAYh PA1KBqt9MTPkOaRmwNKyaeVtxSpujdgR+kEAi1rWiubzPVf6zbHGEnmWzI30t+uN r5Ce0wgkpawOl4AA01T6T4iqkO1OEHlmJTveGrcBVwnCse7VPkJoQaD6G8nTyz55 LcOqukYuniHNWDs2gAnbMSwjZ3tEL3RJ1/4XjW//15gzAGqs05xCpElL7ceSKlBM 9gt9EHfiO9Q5oDICkHE3CitJPTS12OUa11vqd4sF/gmdso8p1BpbD+nmjImYEwv8 +pJ7GFTDB3HM4UfY6QWz =2PKw -----END PGP SIGNATURE----- --Gx6yhVhPSPzNJpj4--
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