Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262705AbVE1LYX (ORCPT ); Sat, 28 May 2005 07:24:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262702AbVE1LYX (ORCPT ); Sat, 28 May 2005 07:24:23 -0400 Received: from smtp001.mail.ukl.yahoo.com ([217.12.11.32]:36486 "HELO smtp001.mail.ukl.yahoo.com") by vger.kernel.org with SMTP id S262699AbVE1LYJ (ORCPT ); Sat, 28 May 2005 07:24:09 -0400 From: Blaisorblade To: Chris Wedgwood , Bodo Stroesser Subject: Re: [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release Date: Sat, 28 May 2005 13:26:15 +0200 User-Agent: KMail/1.7.2 Cc: akpm@osdl.org, jdike@addtoit.com, linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, mingo@redhat.com References: <20050527003926.1FD861AEE92@zion.home.lan> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200505281326.15519.blaisorblade@yahoo.it> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2881 Lines: 65 On Friday 27 May 2005 04:11, Chris Wedgwood wrote: > On Fri, May 27, 2005 at 02:39:26AM +0200, blaisorblade@yahoo.it wrote: > > From: Paolo 'Blaisorblade' Giarrusso , Chris > > Wedgwood CC: Ingo Molnar > > [...] > > > This is heavily based on some work by Chris Wedgwood, which however > > didn't get the patch merged for something I'd call a > > "misunderstanding" (the need for this patch wasn't cleanly > > explained, thus adding the generic hook was felt as undesirable). > Looks very reasonable to me and your explaination is much better than > mine was :-) Yes, it took some time to me to go working on this and getting the time to explain it clearly. > > diff -puN kernel/irq/manage.c~uml-gen-irq-release kernel/irq/manage.c > > --- linux-2.6.git/kernel/irq/manage.c~uml-gen-irq-release 2005-05-25 > > 01:15:46.000000000 +0200 +++ > > linux-2.6.git-paolo/kernel/irq/manage.c 2005-05-25 01:15:46.000000000 > > +0200 @@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *de > > > > /* Found it - now remove it from the list of entries */ > > *pp = action->next; > > + > > + if (desc->handler->release) > > + desc->handler->release(irq, dev_id); > > + > > Because right now we know the *only* port that needs a release method > is UML I wonder if we could do save a couple of bytes & cycles for > everyone else by doing something like #ifdef CONFIG_IRQ_HAS_RELEASE, > #endif around that and then letting the Kconfig magic set > CONFIG_IRQ_HAS_RELEASE as required? If other arches need it thay can > do the same and if eventually almost everyone does we can kill the > #ifdef crud? Well, that's a point, even because a conditional jump needs to flush the pipeline when mispredicted (which won't happen on other ARCHs after the initial period, if this jump stays in the Branch Target Buffers). > Longer term I wonder if some of the irq mechanics in UML couldn't end > up being a bit more like the s390 stuff too? Christoph Hellwig too suggested this, however anything such *must* be longer term (while this was earlier pointed as a reason to drop this patch, last time). Beyond that, I've not a clear understanding of S390, so I cannot for now help (including any merit discussion) on this point... Bodo Stroesser is porting UML on S390 so probably he might help more on this point. -- Paolo Giarrusso, aka Blaisorblade Skype user "PaoloGiarrusso" Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it - 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/