From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.free-electrons.com ([88.190.12.23]) by bombadil.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1ScLe2-00059q-OU for linux-mtd@lists.infradead.org; Wed, 06 Jun 2012 19:11:51 +0000 Received: from skate (AToulouse-555-1-5-124.w92-156.abo.wanadoo.fr [92.156.88.124]) by mail.free-electrons.com (Postfix) with ESMTPSA id 5B26AE5 for ; Wed, 6 Jun 2012 21:11:31 +0200 (CEST) Date: Wed, 6 Jun 2012 21:11:25 +0200 From: Thomas Petazzoni To: linux-mtd@lists.infradead.org Subject: Re: Q: Cramfs Vs. Ubifs Message-ID: <20120606211125.62aba982@skate> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello, Ricard has already answered your points, but I felt that adding an additional detail would be useful. See below. Le Mon, 4 Jun 2012 21:17:34 +0200, Ran Shalit a =C3=A9crit : > I read about cramfs and ubifs, but there is still something I don't > understand here, I hope you can help me with that... > 1. It seems reasonable that execution from RAM is faster then Nand flash. > So If I'm using ubifs, should I copy the executables to RAM before ex= ecute ? This is not needed. The Linux kernel uses the MMU to do demand paging so load on demand into RAM the portions of the program that are actually being used. So Linux userspace applications are always executed from RAM (unless, as Ricard pointed out, you use some XIP mechanism, but that requires NOR flash and special filesystems, so it's a very uncommon situation these days). However, an application is not completely loaded at once at the beginning of its execution, parts of it are loaded on demand during the execution. Best regards, Thomas --=20 Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com