From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [Linux-fbdev-devel] Re: radeon, apertures & memory mapping Date: Tue, 15 Mar 2005 08:54:35 +1100 Message-ID: <1110837275.5863.19.camel@gaston> References: <20050313082216.GA7362@sci.fi> <1110705646.14684.126.camel@gaston> <20050313103936.GA11002@sci.fi> <1110715499.14684.132.camel@gaston> <9e473391050313081937cde207@mail.gmail.com> <1110750553.5787.155.camel@gaston> <9e47339105031314101c89e50e@mail.gmail.com> <1110752401.19810.177.camel@gaston> <9e47339105031315002a444f00@mail.gmail.com> <16948.56755.114690.200854@cargo.ozlabs.ibm.com> <20050314005613.GA21434@sci.fi> <1110762359.19810.209.camel@gaston> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: xorg-bounces@lists.freedesktop.org Errors-To: xorg-bounces@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" To: Soeren Sandmann Cc: Paul Mackerras , Jon Smirl , Linux Fbdev development list , dri-devel@lists.sourceforge.net, xorg@lists.freedesktop.org On Mon, 2005-03-14 at 17:30 +0100, Soeren Sandmann wrote: > Benjamin Herrenschmidt writes: > > > In an ideal world ... However, since we are planning to move the memory > > manager to the kernel, that would mean a kernel access (syscall, ioctl, > > whatever...) twice per access to AGP memory. Not realistic. > > Could the user space driver batch many such accesses together and use > a lock_many()/unlock_many() API? We may have to use a lock/unlock API anyway due to interaction with the VGA arbiter in fact. If for some reason, the card can't completely disable decoding of VGA and IO space, it needs to bracket any access to the framebuffer with something. That is unuseable for things like MOL though. We are giving the framebuffer to some foreign OS in an emulation shell that doesn't know how to do but blit directly at any time. Oh well, I need to think a bit more about those sceniario. Ben.