Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161292AbWHDUjG (ORCPT ); Fri, 4 Aug 2006 16:39:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161403AbWHDUjG (ORCPT ); Fri, 4 Aug 2006 16:39:06 -0400 Received: from warden-p.diginsite.com ([208.29.163.248]:13472 "HELO warden.diginsite.com") by vger.kernel.org with SMTP id S1161292AbWHDUjF (ORCPT ); Fri, 4 Aug 2006 16:39:05 -0400 Date: Fri, 4 Aug 2006 13:31:47 -0700 (PDT) From: David Lang X-X-Sender: dlang@dlang.diginsite.com To: Jeremy Fitzhardinge cc: Arjan van de Ven , Antonio Vargas , Rusty Russell , Andrew Morton , jeremy@xensource.com, greg@kroah.com, zach@vmware.com, linux-kernel@vger.kernel.org, torvalds@osdl.org, hch@infradead.org, jlo@vmware.com, xen-devel@lists.xensource.com, simon@xensource.com, ian.pratt@xensource.com Subject: Re: A proposal - binary In-Reply-To: <44D3A9F3.2000000@goop.org> Message-ID: References: <44D1CC7D.4010600@vmware.com> <20060803190605.GB14237@kroah.com> <44D24DD8.1080006@vmware.com> <20060803200136.GB28537@kroah.com> <44D2B678.6060400@xensource.com> <20060803211850.3a01d0cc.akpm@osdl.org> <1154667875.11382.37.camel@localhost.localdomain> <20060803225357.e9ab5de1.akpm@osdl.org> <1154675100.11382.47.camel@localhost.localdomain> <69304d110608041146t44077033j9a10ae6aee19a16d@mail.gmail.com> <44D39F73.8000803@linux.intel.com> <44D3A9F3.2000000@goop.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2513 Lines: 50 On Fri, 4 Aug 2006, Jeremy Fitzhardinge wrote: >> so if I understand this correctly we are saying that a kernel compiled to >> run on hypervisor A would need to be recompiled to run on hypervisor B, and >> recompiled again to run on hypervisor C, etc >> >> where A could be bare hardware, B could be Xen 2, C could be Xen 3, D could >> be vmware, E could be vanilla Linux, etc. > > Yes, but you can compile one kernel for any set of hypervisors, so if you > want both Xen and VMI, then compile both in. (You always get bare hardware > support.) how can I compile in support for Xen4 on my 2.6.18 kernel? after all xen 2 and xen3 are incompatable hypervisors so why wouldn't xen4 (and I realize there is no xen4 yet, but there is likly to be one during the time virtual servers created with 2.6.18 are still running) >> this sounds like something that the distros would not support, they would >> pick their one hypervisor to support and leave out the others. the big >> problem with this is that the preferred hypervisor will change over time >> and people will be left with incompatable choices (or having to compile >> their own kernels, including having to recompile older kernels to support >> newer hypervisors) > > Why? That's like saying that distros will only bother to compile in one scsi > driver. > > The hypervisor driver is tricker than a normal kernel device driver, because > in general it needs to be present from very early in boot, which precludes it > from being a normal module. There's hope that we'll be able to support > hypervisor drivers as boot-time grub/multiboot modules, so you'll be able to > compile up a new hypervisor driver for a particular kernel and use it without > recompiling the whole thing. distros don't offer kernels with all options today, why would they in the future (how many distros offer seperate 486/586/K6/K7/Pentium/P2/P3/P4 kernels, none. they offer a least-common denominator kernel or two instead) I also am missing something here. how can a system be compiled to do several different things for the same privilaged opcode (including running that opcode) without turning that area of code into a performance pig as it checks for each possible hypervisor being present? David Lang - 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/