From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from inx.pm.waw.pl ([195.116.170.130]) by bombadil.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SM1jY-0003w0-GU for barebox@lists.infradead.org; Sun, 22 Apr 2012 18:42:05 +0000 From: Krzysztof Halasa Date: Sun, 22 Apr 2012 20:38:50 +0200 Message-ID: MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: ARM page 0 set for page fault To: barebox@lists.infradead.org Hi, I'm trying to port my old IXP4xx (Intel XScale ARM big-endian mostly) patches to the current Barebox. Noticed the page #0 (virtual = physical addresses 0 - 0x1FFF, or the first 4 KiB of RAM) is not present: commit abcf935e Author: Sascha Hauer Date: Sun Aug 7 19:00:56 2011 +0200 ARM mmu: use high vectors if possible Using high vectors allows us to map a faulting zero page to catch NULL pointer dereferences. Unfortunately this causes "md" (memory dump) etc. to fail (also executing Linux kernel fails since the tags are located at 0x100 - should I relocate them?). Should I do it differently, e.g. access RAM through an alias (IXP4xx has RAM aliased all over the place, one could also use MMU tables for this) so that the page fault only occurs on internal, not user-visible accesses (= users should not be able to access the first virtual page, even it they think the do)? -- Krzysztof Halasa _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox