From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.ebshome.net (gate.ebshome.net [64.81.67.12]) (using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits)) (Client CN "gate.ebshome.net", Issuer "gate.ebshome.net" (not verified)) by ozlabs.org (Postfix) with ESMTP id 379AA67A6C for ; Sat, 16 Apr 2005 08:12:38 +1000 (EST) Date: Fri, 15 Apr 2005 15:12:35 -0700 From: Eugene Surovegin To: Shawn Jin Message-ID: <20050415221235.GA29802@gate.ebshome.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: ppcembed Subject: Re: Interrupt prioritization on linux for ppc440 List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Apr 15, 2005 at 02:36:51PM -0700, Shawn Jin wrote: > > The home-made interrupt controller PIC supports interrupt priorities > and critical/non-critical interrupts. I found that the current kernel > doesn't support interrupt priorities. Yes, we don't have IRQ priorities on 4xx. Theoretically, they can be emulated in get_irq, but I really don't think it's worth it. > Is this observation true? Is > there any existing patch to support that? I'm not aware of such patch existence. > I noticed that the implementation of ppc4xx_pic.c disables all > critical interrupts during initialization. To support critical > interrupts, is it so simple that we change the handler of critical > exception from CriticalInput to do_IRQ in head_44x.S? No, it's not that simple. Linux doesn't support a notion of critical IRQs versus normal ones. Until there is an infrastructure for this, it doesn't make any sense to implement 4xx support. -- Eugene