From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750760AbWGBAFp (ORCPT ); Sat, 1 Jul 2006 20:05:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751138AbWGBAFp (ORCPT ); Sat, 1 Jul 2006 20:05:45 -0400 Received: from thunk.org ([69.25.196.29]:61107 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id S1750760AbWGBAFo (ORCPT ); Sat, 1 Jul 2006 20:05:44 -0400 Date: Sat, 1 Jul 2006 20:05:28 -0400 From: Theodore Tso To: Linus Torvalds Cc: Jeff Bailey , "H. Peter Anvin" , Michael Tokarev , Roman Zippel , klibc@zytor.com, linux-kernel@vger.kernel.org, Pavel Machek Subject: Re: [klibc] klibc and what's the next step? Message-ID: <20060702000528.GA15375@thunk.org> Mail-Followup-To: Theodore Tso , Linus Torvalds , Jeff Bailey , "H. Peter Anvin" , Michael Tokarev , Roman Zippel , klibc@zytor.com, linux-kernel@vger.kernel.org, Pavel Machek References: <20060630181131.GA1709@elf.ucw.cz> <44A5AE17.4080106@tls.msk.ru> <44A5B07E.9040007@zytor.com> <1151751417.2553.8.camel@localhost.localdomain> <20060701150506.GA10517@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.11 X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 01, 2006 at 01:08:17PM -0700, Linus Torvalds wrote: > The argument that user space is more debuggable has been shown to be > largely a red herring. User space is only more debuggable if it does > something independent, and we've seen that user space is _harder_ to debug > than kernel space if we have events going back and forth. Agreed, 100%. In addition, userspace is debuggable only only if the initramfs has enough debugging code in their (like a real live working shell, strace, basic shell commands etc.) Otherwise, it becomes even more hellish to debug. I wasted a huge amount of time trying to figure out why the RHEL4 initramfs was incompatible with modern kernels using the MPT Fusion SCSI driver, because I couldn't make it stop and break out to a working shell; it had some busybox-like nash thing that wasn't designed for user interaction, so all I could do was try to make tiny changes to the initramfs, wait for the !@#@# very long boot cycle, and watch the initial ramdisk fail to mount the root and crash, and repeat, for hours on end. RHEL4's userspace root mount system was ***not*** more debuggable, not in the last. Adding printk's into a kernel and recompiling would have been easier, and far less frustrating. Hopefully kinit will be better, but it's definitely not the case that userpsace is easier to debug. - Ted