From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UCQM6-00079e-0I for barebox@lists.infradead.org; Mon, 04 Mar 2013 08:02:43 +0000 Date: Mon, 4 Mar 2013 09:02:32 +0100 From: Sascha Hauer Message-ID: <20130304080232.GM25672@pengutronix.de> References: <1361897742-3454-1-git-send-email-maxime.ripard@free-electrons.com> <1361897742-3454-2-git-send-email-maxime.ripard@free-electrons.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1361897742-3454-2-git-send-email-maxime.ripard@free-electrons.com> 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 1/2] memsize: Make get_ram_size RAM proof To: Maxime Ripard Cc: barebox@lists.infradead.org On Tue, Feb 26, 2013 at 05:55:41PM +0100, Maxime Ripard wrote: > get_ram_size cannot be used when running from RAM at the moment, even > though it backs up the memory cells it modifies, since it can also > modify the get_ram_size function itself. > > Avoid testing the memory area where barebox is loaded at to prevent this > problem. If the memory supposed to host barebox is not working, we'll > have plenty of other problems anyway. > > Signed-off-by: Maxime Ripard > --- > common/memsize.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/common/memsize.c b/common/memsize.c > index d149e41..1d00984 100644 > --- a/common/memsize.c > +++ b/common/memsize.c > @@ -19,6 +19,9 @@ > > #include > #include > + > +#include > + > #if defined (__PPC__) && !defined (__SANDBOX__) > /* > * At least on G2 PowerPC cores, sequential accesses to non-existent > @@ -45,6 +48,15 @@ long get_ram_size(volatile long *base, long maxsize) > > for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) { > addr = base + cnt; /* pointer arith! */ > + > + /* > + * If we run get_ram_size from RAM, avoid poking into > + * the Barebox code, and if the RAM at these address > + * doesn't work, we will have trouble anyway... > + */ > + if (addr > (long*)_text && addr < (long*)__bss_stop) > + continue; Unfortunately I had to drop this one. It breaks compilation on some architectures which do not have _text and __bss_stop (namely blackfin and another one I forgot about). Anyway, I realized that we now can start the MMU during early startup, so when you call this function from your board code your SDRAM might already be cached. I assume get_ram_size won't work reliably in this case anymore. Since you only use it to detect whether you have 128MiB or 256Mib, could you code a stripped down version of this function especially for your board? Could you even adjust the SDRAM controller registers to the size you really have? I have no idea if the SDRAM controller can cope with that, but it might be worth giving it a try. I have a patch in the queue moving the i.MX28 over to dynamically detecting the SDRAM size via controller readback, so this then would simply detect the correct size. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 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