From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Deucher Subject: Re: Linux 2.6.39-rc3 Date: Thu, 14 Apr 2011 17:34:46 -0400 Message-ID: References: <20110412090207.GE19819@8bytes.org> <20110412184433.GF19819@8bytes.org> <20110413064609.GA18777@elte.hu> <20110413172147.GI19819@8bytes.org> <4DA5F62F.3030504@kernel.org> <4DA654D6.2060103@zytor.com> <20110414085624.GC18463@8bytes.org> <20110414210932.GG18463@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110414210932.GG18463@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org To: Joerg Roedel Cc: "H. Peter Anvin" , Yinghai Lu , Ingo Molnar , Linus Torvalds , Linux Kernel Mailing List , dri-devel@lists.freedesktop.org, Thomas Gleixner , Tejun Heo List-Id: dri-devel@lists.freedesktop.org On Thu, Apr 14, 2011 at 5:09 PM, Joerg Roedel wrote: > On Thu, Apr 14, 2011 at 10:28:43AM -0400, Alex Deucher wrote: >> On Thu, Apr 14, 2011 at 4:56 AM, Joerg Roedel wrot= e: >> > And this makes a difference, with this change on-top of -rc3 the b= ox boots >> > fine. So there seems to be some dependency between the GART base a= nd the GTT >> > base even when they are in different address spaces. >> > >> > Alex, can you comment on this? >> >> As Dave said, they are completely different addresses spaces. =A0You >> could put the GPU aperture at 0 if you wanted (in fact we do on some >> chips). =A0Perhaps there's some strange interaction with the nb gart >> since the nb gart on that chipset was designed to be used for graphi= cs >> and the rs780/880 can be configured to use an agp aperture. >> Unfortunately, I'm not that familiar with the nb gart. > > Actually, the nb gart is part of the cpu. It is part of the cpu north > bridge and can translate io and cpu accesses. In fact, it is a remapp= er > of physical memory addresses. I know what it's for. In the IGP graphics chip is also part of the north bridge, but it may not be related at all. > > The problem seems to be related to specific gpu chips. On another > notebook with an hd3000 card gtt and the nb gart aperture are both on > 0xa0000000 too but the box works fine. I havn't tested with an hd5000 > yet. The failing notebook has an hd4200 mobility. What exact model is the hd3000? Is it IGP GPU or a discrete GPU? It it's an IGP, it's identical to the hd4200 programming-wise. > > Btw. what happens if the gpu accesses an unmapped address in the gtt > range? It's redirected to a dummy page. Alex