From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964998AbWGIFbA (ORCPT ); Sun, 9 Jul 2006 01:31:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965000AbWGIFbA (ORCPT ); Sun, 9 Jul 2006 01:31:00 -0400 Received: from ug-out-1314.google.com ([66.249.92.174]:21320 "EHLO ug-out-1314.google.com") by vger.kernel.org with ESMTP id S964998AbWGIFa7 (ORCPT ); Sun, 9 Jul 2006 01:30:59 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=PEQSYmycr8PiVRwaxcCTvJAldCB7ctjWQRZzuHaMOKzK0YoL8U/6Scq/GrAQ+ttzM4ZTVkS3SjiAqsQenceCxwD0rXTNb31ZxU2HskyCxzZmQkcix1id8v/iubVv/4NXNeAfJFAvSAM2e0V1wDprnkqtBJuqPq7yBxAfYi6w68Y= Message-ID: <787b0d920607082230w676ddc62u57962f1fc08cf009@mail.gmail.com> Date: Sun, 9 Jul 2006 01:30:58 -0400 From: "Albert Cahalan" To: rmk+lkml@arm.linux.org.uk, jonsmirl@gmail.com, alan@lxorguk.ukuu.org.uk, efault@gmx.de, greg@kroah.com, linux-kernel@vger.kernel.org Subject: Re: Opinions on removing /proc/tty? MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jon Smirl writes: > On 7/8/06, Mike Galbraith wrote: >> On Fri, 2006-07-07 at 22:56 -0400, Jon Smirl wrote: >>> Does anyone use the info in /proc/tty? The hard coded device >>> names aren't compatible with udev's ability to rename things. >>> >>> There also doesn't appear to be any useful info in the drivers >>> portion that isn't already available in sysfs. I can add some code >>> to make a list of registered line disciplines appear in sysfs. >>> >>> Does anyone have a problem with deleting /proc/tty if >>> ldisc enum support is added to sysfs? >> >> ps uses /proc/tty/drivers, so some coordination would be needed. > > Greg, I just looked at the source for ps and it has a bunch > of fixed code for turning major/minor into /dev/name. Isn't > that something udevinfo should be doing? But looking at the > help for udevinfo I don't see any way to turn a major/minor > into /dev/name. The altermative seems to be search /dev > looking for the right device node. By far, the best thing for procps (ps, top, etc.) would be /proc/*/tty links. Code that, give everybody a year to upgrade, and then... maybe. There is no way I'm going to have the procps run a "udevinfo" program, and I very much dislike relying on oddball libraries. Reliability and performance matter; this isn't some GNOME/KDE thing that can break just because 1 of 200 libraries changed. In order, the procps code tries: 1. /proc/*/tty symlink (effectively commented out) 2. /proc/tty/drivers 3. /proc/*/fd/2 symlink 4. hard-coded guess 5. /proc/*/fd/255 symlink 6. "?" Long ago, procps would search /dev for the mapping. This was too slow to be done directly when ps ran, so a binary file in /etc was used to cache the data. Keeping that file updated was a major problem. BTW, cruft gets ripped out some time after Debian-obsolete no longer supports the old kernels.