From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756013AbaDLCqa (ORCPT ); Fri, 11 Apr 2014 22:46:30 -0400 Received: from mail-by2lp0235.outbound.protection.outlook.com ([207.46.163.235]:15038 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754438AbaDLCq2 (ORCPT ); Fri, 11 Apr 2014 22:46:28 -0400 From: KY Srinivasan To: "H. Peter Anvin" , "x86@kernel.org" , "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , "devel@linuxdriverproject.org" , "olaf@aepfle.de" , "apw@canonical.com" , "jasowang@redhat.com" , "tglx@linutronix.de" , "JBeulich@suse.com" Subject: RE: [PATCH V1 1/1] X86: Probe for PIC and set legacy_pic appropriately Thread-Topic: [PATCH V1 1/1] X86: Probe for PIC and set legacy_pic appropriately Thread-Index: AQHPVeGCk3d5oIQvZEiA/cAVWdUh2psNGFyAgAAueFA= Date: Sat, 12 Apr 2014 02:46:23 +0000 Message-ID: <4ffa16b7f32449d2b445054ce8a51d9e@BY2PR03MB299.namprd03.prod.outlook.com> References: <1397263802-5934-1-git-send-email-kys@microsoft.com> <534881DB.40901@zytor.com> In-Reply-To: <534881DB.40901@zytor.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2601:8:9b00:402:7c67:871b:cd27:65d2] x-forefront-prvs: 01792087B6 x-forefront-antispam-report: SFV:NSPM;SFS:(10009001)(6009001)(428001)(24454002)(13464003)(51704005)(164054003)(479174003)(377454003)(189002)(199002)(2656002)(83072002)(81342001)(83322001)(76576001)(81542001)(99396002)(19580395003)(19580405001)(99286001)(74502001)(85852003)(74316001)(46102001)(79102001)(4396001)(86612001)(86362001)(87936001)(76482001)(33646001)(31966008)(80022001)(74662001)(2201001)(54356999)(50986999)(76176999)(77982001)(92566001)(80976001)(20776003)(77096999)(921003)(1121002)(24736002)(3826001);DIR:OUT;SFP:1101;SCL:1;SRVR:BY2PR03MB298;H:BY2PR03MB299.namprd03.prod.outlook.com;FPR:BCCFF902.9B32AD1A.38E3F3B3.48EDC93B.20232;PTR:InfoNoRecords;MX:1;A:1;LANG:en; Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 X-OriginatorOrg: microsoft.onmicrosoft.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id s3C2lRns008141 > -----Original Message----- > From: H. Peter Anvin [mailto:hpa@zytor.com] > Sent: Friday, April 11, 2014 4:59 PM > To: KY Srinivasan; x86@kernel.org; gregkh@linuxfoundation.org; linux- > kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de; > apw@canonical.com; jasowang@redhat.com; tglx@linutronix.de; > JBeulich@suse.com > Subject: Re: [PATCH V1 1/1] X86: Probe for PIC and set legacy_pic > appropriately > > On 04/11/2014 05:50 PM, K. Y. Srinivasan wrote: > > > > + /* > > + * Check to see if we have a PIC. > > + * Mask all except the cascade and read > > + * back the value we just wrote. If we don't > > + * have a PIC, we will read 0xff as opposed to the > > + * value we wrote. > > + */ > > + outb(probe_val, PIC_MASTER_IMR); > > + probe_val = inb(PIC_MASTER_IMR); > > + if (probe_val == 0xff) { > > + printk(KERN_INFO "Using NULL legacy PIC\n"); > > + legacy_pic = &null_legacy_pic; > > + raw_spin_unlock_irqrestore(&i8259A_lock, flags); > > + return; > > + } > > + > > outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ > > outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ > > > > Again, I would do at least the slave masking above the probe. > > Also, I would compare to make sure we get the probe_val back and compare > with != instead of comparing with ==. Will do. Thanks, K. Y {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I