From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from igw2.watson.ibm.com (igw2.watson.ibm.com [129.34.20.6]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id D429967AC7 for ; Thu, 1 Jun 2006 06:27:05 +1000 (EST) Subject: Re: [PATCH] Provide mechanism for editing builtin command-line in zImage binary. From: Michal Ostrowski To: "Mark A. Greer" In-Reply-To: <20060531200419.GA17052@mag.az.mvista.com> References: <11489544631499-git-send-email-mostrows@watson.ibm.com> <20060530204151.GA31567@mag.az.mvista.com> <1149023558.6507.15.camel@brick> <20060531200419.GA17052@mag.az.mvista.com> Content-Type: text/plain Date: Wed, 31 May 2006 16:26:43 -0400 Message-Id: <1149107204.6507.97.camel@brick> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2006-05-31 at 13:04 -0700, Mark A. Greer wrote: > On Tue, May 30, 2006 at 05:12:37PM -0400, Michal Ostrowski wrote: > > On Tue, 2006-05-30 at 13:41 -0700, Mark A. Greer wrote: > > > On Mon, May 29, 2006 at 10:01:03PM -0400, mostrows@watson.ibm.com wrote: > > I'm curious how the tacked-on dt is expected to interact with the real > > FW dt, > > That's a good question. I was thinking that a tacked on dt would be a > complete replacement for whatever dt came from the fw (but extracting > some info like /memory props). That probably works okay for non-OF > systems but may not work for OF systems b/c there is so much more info > in the OF dt. Someone who knows about OF will have to speak up here. > I've had some experience with trying to edit existing OF trees (i.e. take a G5 OF tree and alter it to reflect the fact that the OS has a hypervisor between it and the HW). It's not a pleasant experience. Thus for OF based systems I'd be very wary of trying to edit the OF tree in arbitrary ways prior to Linux seeing it. > > and in particular how you would expect the interrogation > > of /chosen/bootargs in prom_init.c (using prom_getprop()) to pick up the > > command line value I specify in the tacked-on dt. > > If a flattened dt is used instead of an OF dt the prom_init code isn't used. If we always skip prom_init.c code then we may skip stuff like TCE allocation which is only ever done on the first boot (and never on kexec). -- Michal Ostrowski