From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: To built-in Driver, When the corresponding node under /dev created? Date: Tue, 27 Mar 2012 13:53:20 -0700 Message-ID: <20120327205320.GA20151@kroah.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Li Haifeng Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:33431 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755293Ab2C0Ux0 (ORCPT ); Tue, 27 Mar 2012 16:53:26 -0400 Received: by yhmm54 with SMTP id m54so318263yhm.19 for ; Tue, 27 Mar 2012 13:53:25 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Mar 27, 2012 at 02:39:37PM +0800, Li Haifeng wrote: > As you know, the node under /dev are managed by udevd daemon. Not always, usually the node is created by devtmpfs on most modern distros. > But to the built-in driver module, when the module is probed in kernel > space, udevd daemon doesn't running. So, to ttyS node, when the > built-in driver module was probed, when was the /dev/ttyS created? devtmpfs does it. Also, look at your distro startup code, it sets things up properly when userspace starts up and has udev go through things and set up the nodes then. good luck, greg k-h