Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261550AbVETT1Y (ORCPT ); Fri, 20 May 2005 15:27:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261552AbVETT1Y (ORCPT ); Fri, 20 May 2005 15:27:24 -0400 Received: from witte.sonytel.be ([80.88.33.193]:54204 "EHLO witte.sonytel.be") by vger.kernel.org with ESMTP id S261550AbVETT1S (ORCPT ); Fri, 20 May 2005 15:27:18 -0400 Date: Fri, 20 May 2005 21:26:59 +0200 (CEST) From: Geert Uytterhoeven To: "Richard B. Johnson" cc: Jan-Benedict Glaw , Linux kernel Subject: Re: Screen regen buffer at 0x00b8000 In-Reply-To: Message-ID: References: <20050520141434.GZ2417@lug-owl.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1716 Lines: 45 On Fri, 20 May 2005, Richard B. Johnson wrote: > On Fri, 20 May 2005, Jan-Benedict Glaw wrote: > > On Fri, 2005-05-20 09:48:35 -0400, Richard B. Johnson > > wrote: > > > len = getpagesize(); > > > if((fd = open("/dev/mem", O_RDWR)) == FAIL) > > > ERRORS("open"); > > > if((sp = mmap((void *)SCREEN, len, PROT, TYPE, fd, > > > SCREEN))==MAP_FAILED) > > > ERRORS("mmap"); > > > > Maybe you'd better not fiddle with physical memory, but use the device > > abstraction that's ment to offer that interface? That is, use a > > framebuffer driver and open /dev/fb* . /dev/vcs*? > No room for any more drivers. This just writes to a small LCD on an > embedded controller. There should be no reason why I can't > write directly to the physical memory. Anything written to the > physical screen buffer will show up on the screen, as long > as page zero is selected. > > I think that I've discovered a bug. I know that what I have written gets > to the screen buffer because I can read in back! This doesn't make > any sense. Even if it's only in the CPU cache, of course you can read it back (using the CPU, not DMA ;-). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/