From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id A754267C5F for ; Mon, 20 Nov 2006 07:41:18 +1100 (EST) Subject: Re: [PATCH] 2.6.18-rt7: PowerPC: fix breakage in threaded fasteoi type IRQ handlers From: Benjamin Herrenschmidt To: Sergei Shtylyov In-Reply-To: <4560C121.30403@ru.mvista.com> References: <200611192243.34850.sshtylyov@ru.mvista.com> <1163966437.5826.99.camel@localhost.localdomain> <20061119200650.GA22949@elte.hu> <1163967590.5826.104.camel@localhost.localdomain> <4560BDF5.400@ru.mvista.com> <1163968376.5826.110.camel@localhost.localdomain> <4560C121.30403@ru.mvista.com> Content-Type: text/plain Date: Mon, 20 Nov 2006 07:41:25 +1100 Message-Id: <1163968885.5826.116.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Ingo Molnar , linux-kernel@vger.kernel.org, dwalker@mvista.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > This is not implicit -- CPU has to read INTACK reg. on OpenPIC. Which is what I meant... "implicit by reading the vector". > Really implicit method is in action on x86 where CPU issues dual ACK bus cycle to get > the vector form 8259... Which you can do on OpenPIC too. It's the same idea. The concept that obtaining the vector performs the ack. > > EOI is a more "high level" thing that some "intelligent" PICs that > > automatically raise the priority do to restore the priority to what it > > was before the interrupt occured. > > Thank you, I know. Even 8259 has the notion of priority and EOI works the > same way here. Ok, so why would you need an ack there then while eoi is just what you need ? :-) Also, that's interesting what you are saying about 8259... I should be able to convert ppc's i8259 to use fasteoi too... Ben.