From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerone Young Subject: Re: [PATCH] Split kvm_vcpu to support new archs. Date: Wed, 24 Oct 2007 21:56:54 -0500 Message-ID: <1193281014.6374.9.camel@thinkpad> References: <42DFA526FC41B1429CE7279EF83C6BDC809A6A@pdsmsx415.ccr.corp.intel.com> <1192737702.21205.17.camel@basalt> <471AF450.9040202@qumranet.com> <1193080681.27520.32.camel@basalt> Reply-To: jyoung5-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, kvm-ppc-devel , "Zhang, Xiantao" , Avi Kivity To: Hollis Blanchard Return-path: In-Reply-To: <1193080681.27520.32.camel@basalt> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org This may be helpful to everyone if Hollis's explanation of container_of didn't help: Lookup up "container_of" or look at the secion named "Lists" at this link: http://www.win.tue.nl/~aeb/linux/lk/lk-2.html It also contains the macro used in the kernel. On Mon, 2007-10-22 at 14:18 -0500, Hollis Blanchard wrote: > On Sun, 2007-10-21 at 08:40 +0200, Avi Kivity wrote: > > > > The usage of the macro is only for an intermediate stage, so this > > patch shows the changes in the data structures, while the next one > > will be littered with code changes due to the changes in the way > > fields are addressed. > > OK. > > What is the plan here Xiantao? If I want to begin PPC integration, > should I submit some patches too (hopefully in areas where we will not > conflict)? Or should I just review your submissions and hold off on PPC > code changes until the dust settles? > > > I was initially in favor of doing > > > > struct kvm_vcpu { > > struct kvm_vcpu_common common; > > ... > > }; > > > > in order to avoid the majority of fields requiring an 'arch.' prefix > > (most fields are arch dependent, very few are common), but using > > container_of() as someone suggested seems to be a better idea. > > Note: container_of() enables the above layout, and I agree with that > approach. To avoid misunderstandings, this is what we're talking about: > > kvm_common_foo(struct kvm_vcpu_common *vcpu) > { > kvm_arch_foo(vcpu); > } > > kvm_common_bar(struct kvm_vcpu_common *vcpu) > { > ... > } > > ---------- > > struct kvm_vcpu_ppc440 { > struct kvm_vcpu_common common; > u32 gpr[32]; > }; > > #define to_ppc440(v) container_of(...) > > kvm_arch_foo(struct kvm_vcpu_common *vcpu) > { > struct kvm_vcpu_ppc440 *ppc440 = to_ppc440(vcpu); > > ppc440->gpr[3] = 0; > > kvm_common_bar(ppc440->common); > } > > I've chosen specific PPC names since I expect to support more than one > PowerPC processor type simultaneously, e.g. "modprobe kvm-powerpc-440 > kvm-powerpc-e500". (This will require some additional "kvm_ppc_ops" > support not shown here.) > > Personally I think "common" is too much typing, but I've left the name > as you suggested for now. :) > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/