From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Ledford Subject: Re: [PATCH] IB/ipath: use arch_phys_wc_add() and require PAT disabled Date: Wed, 29 Apr 2015 12:57:45 -0400 Message-ID: <1430326665.102408.25.camel@redhat.com> References: <1429730795-6721-1-git-send-email-mcgrof@do-not-panic.com> <1430159932.44548.20.camel@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-/oZIuTgZqXwUTxQaC9AR" Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Luis R. Rodriguez" Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mike Marciniszyn List-Id: linux-rdma@vger.kernel.org --=-/oZIuTgZqXwUTxQaC9AR Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2015-04-29 at 09:01 -0700, Luis R. Rodriguez wrote: > On Mon, Apr 27, 2015 at 11:38 AM, Doug Ledford wrot= e: > > On Mon, 2015-04-27 at 09:46 -0700, Luis R. Rodriguez wrote: > >> On Wed, Apr 22, 2015 at 12:26 PM, Luis R. Rodriguez > >> wrote: > >> > From: "Luis R. Rodriguez" > >> > > >> > We are burrying direct access to MTRR code support on > >> > x86 in order to take advantage of PAT. In the future we > >> > also want to make the default behaviour of ioremap_nocache() > >> > to use strong UC, use of mtrr_add() on those systems > >> > would make write-combining void. > >> > > >> > In order to help both enable us to later make strong > >> > UC default and in order to phase out direct MTRR access > >> > code port the driver over to arch_phys_wc_add() and > >> > annotate that the device driver requires systems to > >> > boot with PAT disabled, with the nopat kernel parameter. > >> > > >> > This is a worthy compromise given that the ipath device > >> > driver powers the old HTX bus cards that only work in > >> > AMD systems, while the newer IB/qib device driver > >> > powers all PCI-e cards. The ipath device driver is > >> > obsolete, hardware hard to find and because of this > >> > this its a reasonable compromise to make to require > >> > users of ipath to boot with nopat. > >> > >> Hey folks, I realize its being discussed whether or not to remove the > >> driver entirely from the kernel but in the meantime, is this a > >> reasonable compromise ? > > > > [ trimmed Cc: list to probably the only people that care ] > > > > I would think so. >=20 > OK great, can this be merged then? I am waiting for this patch to help > move forward with deprecating MTRR upstream. I'm generally OK with picking this up and merging it in. However, it relies on pat_enabled being an exported symbol, and that isn't the case. Are you submitting an additional patch via a different tree to make that symbol exported to modules? > > I think we might as well mark this driver as > > deprecated and put a tentative date on removal while we are at it. >=20 > OK great, that can be done as a separate patch. >=20 > > Mike, any specific input here? I would suggest mark it deprecated with > > a planned removal sometime in late 2015/early 2016. >=20 > I will note that feature-removal file was removed from Linux so if we > want to deprecate something now we just do it. >=20 > Luis > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=20 Doug Ledford GPG KeyID: 0E572FDD --=-/oZIuTgZqXwUTxQaC9AR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJVQQ2JAAoJELgmozMOVy/dl8MP/jBv1OvFRByZ/eM+iY2KMBa7 gDlv6NAHE2jgzAfLpjCsmSnwcggGbfhXTozZ2yETU6r+Z8Ak+atU4XMchceGoHxn vrsIsuT2a7sMtMhoxQDFpzD4hmUaO8oGVQP0r1izbeRFroeEBO12VzOtHZhONvIL 4PGmwJ0t98sqKlOc3puemai1rktKG7rZviKGD9ptefXH28FifktW76yYLjgSxQmV 3K86XI2gh3N0UfpoBEyGc5xmbccUPK3zCbeBhCOVtCRpNtt1gddjeJDCvPEqIgiJ bSMxD064kFJhxwEengrTP81pgFOgGUbH5lMnvLhZgsCm4Uxg3ciDyqbB8B0T/57U oMMgdwzljtYWX+DNqo9x9FbV9UBvzZUtypxpvtgccIGUIps9sSqFLJHlTGfg9t3m w4ICpU8uIWhSaSuxH8DZ3m2dMm93NT5vd8OVRJw5wAFwsXdylm3LKgZIptF7ZU7A dTqs2pA+9HCEx3id4ACSzXtdc4TjLm2zVYinz4JgfrNy6Rs6F4ANJw2vCRMVlQ8d yDsTR5NSnTY53g4y39tb9jj76NYNuHtX+D+5tbkqYgO6E+SQ1tYxTMUPbcP+J8s8 mSyyll2O0q2Sjh5l4S8c4riJjDRQ65ZOdatOMt+0hO979lsmCRYduCakHTwajs9L FCq5k4vSHLv2Gbw721HH =YVak -----END PGP SIGNATURE----- --=-/oZIuTgZqXwUTxQaC9AR-- -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html