From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756680AbYE3Dgi (ORCPT ); Thu, 29 May 2008 23:36:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752916AbYE3Dg1 (ORCPT ); Thu, 29 May 2008 23:36:27 -0400 Received: from ozlabs.org ([203.10.76.45]:48730 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752104AbYE3Dg0 (ORCPT ); Thu, 29 May 2008 23:36:26 -0400 From: Rusty Russell To: Christian Borntraeger Subject: Re: [Patch/RFC]: check CONFIG_GENERIC_HARDIRQS for request/free_irq in interrupt.h Date: Fri, 30 May 2008 13:36:02 +1000 User-Agent: KMail/1.9.9 Cc: schwidefsky@de.ibm.com, LKML , Ingo Molnar , Thomas Gleixner , Stephen Rothwell , will schmidt References: <200805291741.13956.borntraeger@de.ibm.com> <1212080684.16984.30.camel@localhost> <200805292032.58801.borntraeger@de.ibm.com> In-Reply-To: <200805292032.58801.borntraeger@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200805301336.03317.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 30 May 2008 04:32:58 Christian Borntraeger wrote: > Am Donnerstag, 29. Mai 2008 schrieb Martin Schwidefsky: > > On Thu, 2008-05-29 at 17:41 +0200, Christian Borntraeger wrote: > > > I currently try to evaluate virtio_console for kvm on s390 and got > > > the following problem: > > > > > > virtio_console uses hvc_alloc with irq=0. That means, register_irq > > > and free_irq are never called by hvc_console.c, but the linker will > > > still complain about unknown references to free_irq and request_irq. > > > > > > As the whole kernel/irq folder depends on CONFIG_GENERIC_HARDIRQS > > > it seems consistent to declare all functions from kernel/irq only if > > > CONFIG_GENERIC_HARDIRQS is set. Otherwise we can use empty functions. > > > > > > This patch does that for register_irq and free_irq. > > > > > > Comments? > > > > Please don't. So far whenever the linker complained about the missing > > register_irq/free_irq functions it has been a bug in a Kconfig file. > > We should not silently accept code that requires the concept of an > > irq-line when there is no such thing on a s390. > > Ok, convinced. > > I will look if I can modify virtio_console to get rid of hvc_console. > Reading all the comments, it appears that Rusty is not really happy with > all the dependencies/limitations that hvc_console brings to virtio_console. > > Rusty, be prepared.... ;-) > > Christian OK, my plan was to at least allow the hook of notifiers in hvc_console, rather than relying on interrupts or nothing. Then expose "use interrupt to notify" and "use a backoff timer to notify" helpers and let the caller hook one up. But it was a vague plan which may become unrecognisable when meeting reality... Cheers, Rusty.