From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1IqapO-0007U1-4s for mharc-grub-devel@gnu.org; Fri, 09 Nov 2007 15:51:46 -0500 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1IqapM-0007RU-Sm for grub-devel@gnu.org; Fri, 09 Nov 2007 15:51:44 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1IqapJ-0007Ip-9h for grub-devel@gnu.org; Fri, 09 Nov 2007 15:51:44 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1IqapJ-0007Ij-5E for grub-devel@gnu.org; Fri, 09 Nov 2007 15:51:41 -0500 Received: from aybabtu.com ([69.60.117.155]) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1IqapI-0005Dy-P1 for grub-devel@gnu.org; Fri, 09 Nov 2007 15:51:40 -0500 Received: from [192.168.10.6] (helo=thorin) by aybabtu.com with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from ) id 1IqapG-0002T7-Nq for grub-devel@gnu.org; Fri, 09 Nov 2007 21:51:39 +0100 Received: from rmh by thorin with local (Exim 4.63) (envelope-from ) id 1Iqap3-0006Af-9O for grub-devel@gnu.org; Fri, 09 Nov 2007 21:51:25 +0100 Date: Fri, 9 Nov 2007 21:51:25 +0100 From: Robert Millan To: The development of GRUB 2 Message-ID: <20071109205125.GA23437@thorin> References: <471E4628.9030706@t-online.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <471E4628.9030706@t-online.de> Organization: free as in freedom X-Message-Flag: Microsoft discourages use of Outlook. X-Debbugs-No-Ack: true User-Agent: Mutt/1.5.13 (2006-08-11) X-detected-kernel: by monty-python.gnu.org: Genre and OS details not recognized. Subject: Re: [PATCH] Fix eisa_mmap evaluation, add memory existence check X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GRUB 2 List-Id: The development of GRUB 2 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 09 Nov 2007 20:51:45 -0000 On Tue, Oct 23, 2007 at 09:06:16PM +0200, Christian Franke wrote: > +/* Check memory address */ > +static int > +addr_is_valid (grub_addr_t addr) > +{ > + volatile unsigned char * p = (volatile unsigned char *)addr; > + unsigned char x, y; > + x = *p; > + *p = x ^ 0xcf; > + y = *p; > + *p = x; > + return y == (x ^ 0xcf); > +} > + I have a feeling this might be dangerous. Any comments on the warnings listed here: http://www.osdev.org/wiki/How_Do_I_Determine_The_Amount_Of_RAM#Counting_RAM_by_direct_probing ? Specially the bit about memory-mapped PCI. Besides, if we really want it, perhaps it should be in a separate file so that other ports can use it if it's needed ? Ah, and why 0xcf instead of 0xff ? -- Robert Millan I know my rights; I want my phone call! What use is a phone call, if you are unable to speak? (as seen on /.)