Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422652AbWHEAGk (ORCPT ); Fri, 4 Aug 2006 20:06:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422653AbWHEAGk (ORCPT ); Fri, 4 Aug 2006 20:06:40 -0400 Received: from ozlabs.org ([203.10.76.45]:39298 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1422652AbWHEAGj (ORCPT ); Fri, 4 Aug 2006 20:06:39 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17619.57607.638788.298986@cargo.ozlabs.ibm.com> Date: Sat, 5 Aug 2006 10:06:31 +1000 From: Paul Mackerras To: Theodore Tso Cc: Alan Cox , Zachary Amsden , Greg KH , Linux Kernel Mailing List , Linus Torvalds , Andrew Morton , Christoph Hellwig , Rusty Russell , Jack Lo Subject: Re: A proposal - binary In-Reply-To: <20060804143420.GB16313@thunk.org> References: <44D1CC7D.4010600@vmware.com> <20060803190605.GB14237@kroah.com> <44D24DD8.1080006@vmware.com> <20060803200136.GB28537@kroah.com> <44D26D87.2070208@vmware.com> <1154644383.23655.142.camel@localhost.localdomain> <44D2794A.0@vmware.com> <1154647835.23655.161.camel@localhost.localdomain> <44D28985.8050200@vmware.com> <1154686885.23655.198.camel@localhost.localdomain> <20060804143420.GB16313@thunk.org> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1819 Lines: 41 Theodore Tso writes: > IBM's virtualization *does* have magic blobs; it's called the > hypervisor. The difference is that the PowerPC have a delibierately > castrated architecture such that when you are running a guest > operating system in an LPAR, so that when you do things like mess with > page tables (for example), it traps to the hypervisor which is really Well no. When the kernel wants to change the hardware page tables it doesn't even try to do it itself, it calls the hypervisor via the "hypervisor system call" instruction. It's entirely analogous to a program calling the "write" system call to send output to a terminal rather than trying to drive the serial port directly (via outb instructions or whatever). > "a magic binary blob" running on the bare Power architecture. The Not really. Not any more than the Windows kernel is a "magic binary blob" in a GPL'd program running under Windows. > difference is that the way you trap into the hypervisor is via a > PowerPC instructure that looks like a native instruction call. Wow, you must have been really tired when you wrote that... :) > The bottom line is that the line between magic binary blobs and > whether or not they are legal or not is more of a grey line than we > might want to admit. It's quite clear that (a) being in a separate address space (b) having a defined, documented interface and (c) being used by multiple different client OSes is pretty good evidence that something is an independent work, not a derived work of the kernel, and therefore not subject to the GPL. Paul. - 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/