Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 6 Oct 2001 22:54:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 6 Oct 2001 22:54:40 -0400 Received: from sushi.toad.net ([162.33.130.105]:61405 "EHLO sushi.toad.net") by vger.kernel.org with ESMTP id ; Sat, 6 Oct 2001 22:54:34 -0400 Subject: Re: Linux should not set the "PnP OS" boot flag From: Thomas Hood To: linux-kernel@vger.kernel.org Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Evolution/0.14 (Preview Release) Date: 06 Oct 2001 22:54:37 -0400 Message-Id: <1002423279.978.28.camel@thanatos> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ebiederman@uswest.net wrote: > Hmm. Linux isn't quite a "PnP OS". I agree that in the short > term we should not set the boot flag. But we should also investigate > what needs to added so that setpnp does not need to be called. This change has to be permanent. Linux should never automatically set the boot flag, no matter how PnP-competent we make it. The reason is that setting the flag affects what the BIOS will do on the _subsequent_ boot. But Linux can't possibly know which operating system will be booted _next time_. This is something that has to be left up to the user to control. Assuming I've made that point, I'll go on to say that I do not know of any reason why the PnP-OS flag should _ever_ be set. SFAIK all that setting the flag does is stop the PnP BIOS from configuring devices in the way that it has been told to do (if we used "setpnp -b" to set the nonvolative configuration). I don't see why we would ever want to do this. If the BIOS does configure the devices, nothing stops us from reconfiguring them (using "setpnp") once Linux has booted. The PnP-OS flag is called a "quick boot" flag, but the time savings involved must be on the order of milliseconds. All that we seem to achieve by booting Linux with disabled devices is to induce certain device drivers to segfault. Please let me know if I'm overlooking something. If I'm right, then bootflag.c should be modified (see my patch) to remove the bit that sets the flag. It would be nice, however, if the flag could be controlled via a /proc entry. -- Thomas - 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/