Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758174AbZANKeS (ORCPT ); Wed, 14 Jan 2009 05:34:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753238AbZANKeD (ORCPT ); Wed, 14 Jan 2009 05:34:03 -0500 Received: from nf-out-0910.google.com ([64.233.182.191]:48743 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752805AbZANKeB (ORCPT ); Wed, 14 Jan 2009 05:34:01 -0500 MIME-Version: 1.0 In-Reply-To: <1231926744.11907.12.camel@skunk> References: <496DA678.1090701@wpkg.org> <20090114093422.GA9771@frolo.macqel> <1231926744.11907.12.camel@skunk> Date: Wed, 14 Jan 2009 11:34:00 +0100 Message-ID: Subject: Re: linux kernel without file system From: Kay Sievers To: Xavier Bestel Cc: Philippe De Muyter , Tomasz Chmielewski , LKML Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1729 Lines: 35 On Wed, Jan 14, 2009 at 10:52, Xavier Bestel wrote: > On Wed, 2009-01-14 at 10:34 +0100, Philippe De Muyter wrote: >> On Wed, Jan 14, 2009 at 09:46:48AM +0100, Tomasz Chmielewski wrote: >> >> I need to design a very small embedded system that must only control >> >> one ethernet port and two serial lines and must fit in a very small flash >> >> memory. So I thought about replacing the call to /etc/init by my >> >> application >> >> program and removing all the file-system part of linux. >> >> Is that doable ? >> >> Is there a 'standard' way of doing that ? >> >> The first problem I see is accessing my serial lines. How could I do that >> >> without using open("/dev/ttySx"), which requires a file system ? >> >> Is there a way to access devices that does not require a file-system ? >> > >> > You could put everything in initramfs (and embed it in the kernel). >> >> Actually, I was thinking about reducing the footprint of my kernel by >> removing all the fs-related system calls, so the problem is not where >> the file-system is, but how to access (serial) devices without giving their >> "/dev/..." name. > > You can still mount sysfs somewhere and access the device nodes from > there. There are no device nodes in sysfs to talk to the device, only attributes, which are mostly plain small text files. For some devices there are a few writable and mappable files which can change the device's state, but that's nothing like a device node. Kay -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/