From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH] drm/mm: Support 4 GiB and larger ranges Date: Tue, 27 Jan 2015 09:15:26 +0100 Message-ID: <20150127081523.GA32656@ulmo> References: <1422000306-27926-1-git-send-email-thierry.reding@gmail.com> <54C72B30.5070302@vmware.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1639984451==" Return-path: In-Reply-To: <54C72B30.5070302@vmware.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Thomas Hellstrom Cc: "intel-gfx@lists.freedesktop.org" , dri-devel , Russell King , Daniel Vetter List-Id: dri-devel@lists.freedesktop.org --===============1639984451== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="uAKRQypu60I7Lcqm" Content-Disposition: inline --uAKRQypu60I7Lcqm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 27, 2015 at 07:07:44AM +0100, Thomas Hellstrom wrote: > On 01/26/2015 11:51 PM, Dave Airlie wrote: > > On 23 January 2015 at 18:05, Thierry Reding = wrote: > >> From: Thierry Reding > >> > >> The current implementation is limited by the number of addresses that > >> fit into an unsigned long. This causes problems on 32-bit Tegra where > >> unsigned long is 32-bit but drm_mm is used to manage an IOVA space of > >> 4 GiB. Given the 32-bit limitation, the range is limited to 4 GiB - 1 > >> (or 4 GiB - 4 KiB for page granularity). > >> > >> This commit changes the start and size of the range to be an unsigned > >> 64-bit integer, thus allowing much larger ranges to be supported. > > This seems fine to me, Chris, Daniel or Thomas, any objections? > > > > Dave. >=20 > This is perfectly fine with me, although I'm a bit curious why the > allocation granularity of the IOVA space needs to be 1 byte? Are you referring to the 4 GiB - 1 comment? The point I was trying to make is not that the granularity of the IOVA space needs to be 1 byte but rather that using an unsigned long for a size on a 32-bit machine will give you 4 GiB - 1 addresses. The IOMMU page size is still 4 KiB for Tegra. Thierry --uAKRQypu60I7Lcqm Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJUx0kbAAoJEN0jrNd/PrOhX+IP/0tG+HgSR9sIFyTwQ5a9IbgD ia+UVumjaKgBxj6UNqjWmXMgDFhXOENtxP0Czmf8nXUkFICSMeJKzztGyUe5Mv2F FV0NGIyDyurJSm8t4kDp2HKbbvJHnFO2lmICaNnQldDicztB0GntmaP3sO6mBLYG 9HLH5LVEBqc0kNauCNUKn6OvGH3crGOoV/wtk63aiAJAaYep0ENxuFd67/LaaokH ov8f6fd4KL9xbeDlXV8x8oqfFRVJFN23K+BUcAWWzeU+EOplDSi6LAGiiFGegOTL i68ADmjmG6X2FTD8vhl4XmDYMKmRmDCOH90NwQAKFqu2wqS/WET3g5OeTkstgYfa 2NsazAGnr+heV5+UyLXdCqTUYtwnkj+Q3w6mMCzcEIMcZXMeaM79MFtfgh1jeG/k F3KZKYIZoWDmKudcnebun9NmlJ8jMwvOS69ASPqBaGv/9GTEONUSgLW9KXCzYqgf B07uHfjboU/ZTsavH2nm7mm/stRoqa8LiY8R7zL5fYiJBSNnweKsvLnbmnvtaPCB qkcwQBqxVsHC3xA6uJN0o9EZMU4kBqyfuc4qVZMTLWuOqfs14aTd0n0lZBQQynof jxwf5NRQQ0ecB+Vr347l0m+mQBIj4ELtXY+oUW3uYULOWeXBi1drxncgi79OyC+a J6L/NSSojL9X/A7a3oJB =nGvi -----END PGP SIGNATURE----- --uAKRQypu60I7Lcqm-- --===============1639984451== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KSW50ZWwtZ2Z4 IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0 cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9pbnRlbC1nZngK --===============1639984451==--