From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0910.google.com with SMTP id f1so708631rvb.26 for ; Sun, 30 Mar 2008 16:29:15 -0700 (PDT) Message-ID: <86802c440803301629g6d1b896o27e12ef3c84ded2c@mail.gmail.com> Date: Sun, 30 Mar 2008 16:29:15 -0700 From: "Yinghai Lu" Subject: Re: [RFC 8/8] x86_64: Support for new UV apic In-Reply-To: <20080330211848.GA29105@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080324182122.GA28327@sgi.com> <87abknhzhd.fsf@basil.nowhere.org> <20080325175657.GA6262@sgi.com> <20080326073823.GD3442@elte.hu> <86802c440803301323q5c4bd4f4k1f9bdc1d6b1a0a7b@mail.gmail.com> <20080330210356.GA13383@sgi.com> <20080330211848.GA29105@one.firstfloor.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: Jack Steiner , Ingo Molnar , tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Sun, Mar 30, 2008 at 2:18 PM, Andi Kleen wrote: > > If there was a significant differece between UV and generic kernels > > (or hardware), then I would agree. However, the only significant > > difference is the APIC model on large systems. Small systems are > > exactly compatible. > > > > The problem with subarch is that we want 1 binary kernel to support > > x86-64 subarchs are more options than true subarchs. They generally > do not prevent the kernel from running on other systems, just > control addition of some additional code or special data layout. They are > quite different from the i386 subarchs or those of other architectures. > > The main reason vSMP is called a subarch is that it pads a lot > of data structures to 4K and you don't really want that on your > normal kernel, but there isn't anything in there that would > prevent booting on a normal system. > > The UV option certainly doesn't have this issue. > > > > both generic hardware AND uv hardware. This restriction is desirable > > for the distros and software vendors. Otherwise, additional kernel > > images would have to be built, released, & certified. > > I think an option would be fine, just don't call it a subarch. I don't > feel strongly about it, as you point out it is not really very much > code. if the calling path like GET_APIC_ID is keeping checking if it is UV box after boot time, that may not good. don't need make other hundreds of machine keep running the code only for several big box all the time. YH -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org