From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 4/8] unify paravirt parts of system.h Date: Mon, 17 Dec 2007 01:23:06 +0100 Message-ID: <20071217002306.GD5692__23330.0933301964$1197905537$gmane$org@elf.ucw.cz> References: <11967843881946-git-send-email-gcosta@redhat.com> <20071205163017.GA4756@ucw.cz> <20071215131723.GF9720@elte.hu> <200712170127.31615.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200712170127.31615.rjw@sisk.pl> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Rafael J. Wysocki" Cc: ehabkost@redhat.com, linux-kernel@vger.kernel.org, Andi Kleen , chrisw@sous-sol.org, tglx@linutronix.de, anthony@codemonkey.ws, hpa@zytor.com, akpm@linux-foundation.org, Glauber de Oliveira Costa , virtualization@lists.linux-foundation.org, Ingo Molnar List-Id: virtualization@lists.linuxfoundation.org On Mon 2007-12-17 01:27:29, Rafael J. Wysocki wrote: > On Saturday, 15 of December 2007, Ingo Molnar wrote: > > > > * Pavel Machek wrote: > > > > > > Linux never uses that register. The only user is suspend > > > > save/restore, but that' bogus because it wasn't ever initialized by > > > > Linux in the first place. It could be probably all safely removed. > > > > > > It probably is safe to remove... but we currently support '2.8.95 > > > kernel loads/resumes 2.6.24 image'... which would break if 2.8 uses > > > cr8. > > > > > > So please keep it if it is not a big problem. > > > > hm, so __save_processor_state() is in essence an ABI? Could you please > > also send a patch that documents this prominently, in the structure > > itself? > > Hmm, I'm not sure if it really is an ABI part. It doesn't communicate anything > outside of the kernel in which it is defined. Well, it is not "application binary interface", but it is "kernel-to-kernel binary interface"... > The problem is, though, that if kernel A is used for resuming kernel B, and > kernel B doesn't save/restore everything it will need after the resume, then > things will break if kernel A modifies that. So, yes, we'll need to document > that explicitly. Agreed. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html