Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759492AbZANLCU (ORCPT ); Wed, 14 Jan 2009 06:02:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753923AbZANLCJ (ORCPT ); Wed, 14 Jan 2009 06:02:09 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:56115 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753332AbZANLCI (ORCPT ); Wed, 14 Jan 2009 06:02:08 -0500 Date: Wed, 14 Jan 2009 12:01:42 +0100 From: Ingo Molnar To: Jaswinder Singh Rajput Cc: Jaswinder Singh Rajput , "Maciej W. Rozycki" , Alexey Starikovskiy , Yinghai Lu , paul.s.diefenbaugh@intel.com, jun.nakajima@intel.com, Alan Cox , x86 maintainers , LKML , Thomas Gleixner , "H. Peter Anvin" Subject: Re: [PULL -tip] x86: replacing mp_config_X with mpc_X Message-ID: <20090114110142.GJ2913@elte.hu> References: <1231764478.10461.5.camel@jaswinder.satnam> <20090112131100.GA670@elte.hu> <3f9a31f40901140224o5de6d6ecj136d05ca2ba40e92@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3f9a31f40901140224o5de6d6ecj136d05ca2ba40e92@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3397 Lines: 101 * Jaswinder Singh Rajput wrote: > On Mon, Jan 12, 2009 at 6:41 PM, Ingo Molnar wrote: > > > > * Jaswinder Singh Rajput wrote: > > > >> -struct mp_config_ioapic { > >> - unsigned long mp_apicaddr; > >> - unsigned int mp_apicid; > >> - unsigned char mp_type; > >> - unsigned char mp_apicver; > >> - unsigned char mp_flags; > >> -}; > >> - > >> -struct mp_config_intsrc { > >> - unsigned int mp_dstapic; > >> - unsigned char mp_type; > >> - unsigned char mp_irqtype; > >> - unsigned short mp_irqflag; > >> - unsigned char mp_srcbus; > >> - unsigned char mp_srcbusirq; > >> - unsigned char mp_dstirq; > >> -}; > > > > So you replaced that with mpc_ioapic and mpc_intsrc uses: > > > > struct mpc_ioapic { > > unsigned char type; > > unsigned char apicid; > > unsigned char apicver; > > unsigned char flags; > > unsigned int apicaddr; > > }; > > > > struct mpc_intsrc { > > unsigned char type; > > unsigned char irqtype; > > unsigned short irqflag; > > unsigned char srcbus; > > unsigned char srcbusirq; > > unsigned char dstapic; > > unsigned char dstirq; > > }; > > > > And removed the mp_config_ioapic and mp_config_intsrc types. > > > > The mp_config_ioapic and mp_config_intsrc types are kernel-internal, while > > mpc_ioapic and mpc_intsrc is an MP Specification type - the lowlevel > > structure of these tables as provided in RAM or ROM by the BIOS. > > > > Here's the potential problems that need to be thought through: > > > > - the biggest potential problem is that apicaddr is 32-bit wide while > > mp_apicaddr is 64-bit wide, on the 64-bit kernel. Can an apic address be > > above 4 GB, in an mptable? I dont think it can be. > > > > mp_apicaddr is getting its value from apicaddr which is u32 > (arch/x86/kernel/acpi/boot.c) > OR > mp_apicaddr is getting its value from apicaddr which is u32 > (arch/x86/kernel/mpparse.c) > > > - another problem could be that dstapic are all 1-byte entities - while in > > the in-kernel version (mp_apicid and mp_dstapic) they are 32 bit. The > > ACPI code fills in the tables too so maybe there it can be wider than 8 > > bits? > > > > mp_apicid is getting its value from uniq_ioapic_id(id) which returns > u8 (arch/x86/kernel/acpi/boot.c) > OR > mp_apicid is getting its value from reg_00.bits.ID which also 8 bits > (arch/x86/kernel/io_apic.c) > OR > mp_apicid is getting its value from apicid which also 8 bits > (arch/x86/kernel/mpparse.c) > > and > > mp_dstapic is getting its value from mp_apicid which is already 8 bits > (arch/x86/kernel/acpi/boot.c) > OR > mp_dstapic is getting its value from mpc_intsrc->dstapic which is > already 8 bits (arch/x86/kernel/mpparse.c) > > By using current structure we are wasting space as well as creating > confusion for checking u8 <-> u32 and u32 <-> u64. ok, that sounds fair enough - double-checking that we are not introducing some stupid limit somewhere was important. I've pulled your two cleanup commits, thanks, Ingo -- 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/