From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: Mapping the framebuffer into kernel space Date: Thu, 28 Apr 2005 23:55:28 -0400 Message-ID: <9e473391050428205517f3c8c0@mail.gmail.com> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1DRMbH-0003Zh-DU for linux-fbdev-devel@lists.sourceforge.net; Thu, 28 Apr 2005 20:55:35 -0700 Received: from wproxy.gmail.com ([64.233.184.198]) by sc8-sf-mx2.sourceforge.net with esmtp (Exim 4.41) id 1DRMbH-00013A-1c for linux-fbdev-devel@lists.sourceforge.net; Thu, 28 Apr 2005 20:55:35 -0700 Received: by wproxy.gmail.com with SMTP id 69so814826wri for ; Thu, 28 Apr 2005 20:55:28 -0700 (PDT) Content-Disposition: inline Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: fbdev , "Antonino A. Daplas" I looked at a few fbdev drivers and they are mapping the framebuffer into kernel space. Example from radeonfb: rinfo->mapped_vram =3D min_t(unsigned long, MAX_MAPPED_VRAM, rinfo->video= _ram); do { rinfo->fb_base =3D ioremap (rinfo->fb_base_phys, rinfo->mapped_vram); Isn't the only consumer of this kernel mapping fbconsole? If so shouldn't fbconsole be doing the mapping instead of doing it in the drivers? Doing it in fbconsole would let us map exactly the amount of VRAM needed for the console. Right now the driver has to guess the maximum consumption. This would minimize the amount of kernel address space consumed by fbdev. It could also remove a bunch of redundant code. Then in my case where I'm running radeonfb but not fbconsole there would be no kernel address space consumed at all. Minimizing kernel address space consumption is important for x86 systems with more than 1GB of memory. Address space going to fbdev pushes system pages from low into high memory and slows them down. --=20 Jon Smirl jonsmirl@gmail.com ------------------------------------------------------- SF.Net email is sponsored by: Tell us your software development plans! Take this survey and enter to win a one-year sub to SourceForge.net Plus IDC's 2005 look-ahead and a copy of this survey Click here to start! http://www.idcswdc.com/cgi-bin/survey?id=105hix