From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVV4C-0003nm-RX for barebox@lists.infradead.org; Thu, 22 Oct 2020 07:31:21 +0000 Date: Thu, 22 Oct 2020 09:31:19 +0200 From: Sascha Hauer Message-ID: <20201022073119.GN26805@pengutronix.de> References: <20201021145140.597728-1-m.tretter@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201021145140.597728-1-m.tretter@pengutronix.de> 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" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v3 1/2] ARM: mmu64: allow to disable null pointer trap on zero page To: Michael Tretter Cc: barebox@lists.infradead.org On Wed, Oct 21, 2020 at 04:51:39PM +0200, Michael Tretter wrote: > Barebox uses the zero page to trap NULL pointer dereferences. However, > if the SDRAM starts at address 0x0, this makes the first page of the > SDRAM inaccessible and makes it impossible to load images to offset 0x0 > in the SDRAM. > > Trapping NULL pointer dereferences on such systems is still desirable. > Therefore, add a function to disable the traps if accessing the zero > page is necessary and to re-enable the traps after the access is done. > > The zero_page_memcpy function simplifies copying to the SDRAM, because > this is the most common required functionality, but memtest also > accesses the zero page and does not use memcpy. > > Signed-off-by: Michael Tretter Applied, thanks Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox