From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCHEs]: support more than 32 VCPUs in guests Date: Mon, 26 Jul 2010 15:57:51 -0700 Message-ID: <4C4E12EF.6070108@goop.org> References: <20100609160920.1445fbbe@mantra.us.oracle.com> <4C102742.3010108@goop.org> <20100609170825.06a67ff9@mantra.us.oracle.com> <4C1036B0.4060905@goop.org> <20100609191332.588a15d1@mantra.us.oracle.com> <4C15F85A.1050804@goop.org> <20100614194926.2f81ed3d@mantra.us.oracle.com> <4C173A2B.2050701@goop.org> <20100615114543.644442a9@mantra.us.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100615114543.644442a9@mantra.us.oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Mukesh Rathor Cc: "Xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On 06/15/2010 11:45 AM, Mukesh Rathor wrote: > On Tue, 15 Jun 2010 09:30:35 +0100 > Jeremy Fitzhardinge wrote: > >> On 06/15/2010 03:49 AM, Mukesh Rathor wrote: >>> On Mon, 14 Jun 2010 10:37:30 +0100 >>> Jeremy Fitzhardinge wrote: >>> >>> >>>> On 06/10/2010 03:13 AM, Mukesh Rathor wrote: >>>> >>>>> Well, BUG_ON is only triggered if booting more than 32 VCPUs on a >>>>> *very old* xen (pre xen 3.1.0). >>>>> >>>>> Looking at code closely, we could just set setup_max_cpus to 32 >>>>> some where in xen function, perhaps even in xen_vcpu_setup(). >>>>> That way later in smp_init() it would just be ok. >>>>> >>>>> >>>> Yes. >>>> >>>> >>>>> One thing tho, the per cpus areas are already setup at that point, >>>>> so that would need to be cleaned. BTW, I don't understand why >>>>> have_vcpu_info_placement is set to 0 in xen_guest_init()? >>>>> >>>>> >>>> xen_guest_init is used by the pvhvm path, and hvm domains don't >>>> have a notion of vcpu info placement. >>>> >>>> >>>>> What minimum version of xen is required to run pvops kernel? >>>>> >>>>> >>>> In theory it should be back-compatible for all Xen 3, but in >>>> practice it tweaks lots of bugs in older Xens (particularly >>>> 32-on-64). I don't know that anyone has definitively established >>>> an earliest version. I implemented vcpu info placement for use in >>>> pvops kernels, but it was never my intention that it be an >>>> absolute requirement. >>>> >>>> J >>>> >>> Ok, attached patch without BUG_ON. Please feel free to modify >>> to your liking also. >>> >> It looks like you smashed all the tabs into spaces so its hard to see >> what you've changed in the diff. I'll fix it up and give it a >> look-over. >> >> J > Sorry, I've tabs turned off because patches I submit to other product I > work on must be tab free. Anyways, re attached a new one with tabs. This doesn't compile with CONFIG_SMP=n because setup_max_cpus doesn't exist. For now I've just put a couple of #ifdef CONFIG_SMPs in there to avoid compile errors, but could you look at coming up with a cleaner solution? Thanks, J