On Fri, 5 Apr 2013, Rob Herring wrote: > On 04/05/2013 02:36 PM, Nicolas Pitre wrote: > > On Fri, 5 Apr 2013, Stefano Stabellini wrote: > > > >> This is what happens: > >> > >> - No Xen > >> Xen is not running on the platform and a Xen hypervisor node is not > >> available on device tree. > >> Everything keeps working seamlessly, this patch doesn't change anything. > >> > >> - we are running on Xen > >> Xen is running on the platform, we are running as a guest on Xen and an > >> hypervisor node is available on device tree. > >> Let's also assume that there aren't any "arm,cci" compatible nodes on > >> device tree because Xen wouldn't export this kind of information to any > >> guests right now. Therefore PSCI should be used to boot secondary cpus. > >> Because the versatile express machine sets smp_init to > >> vexpress_smp_init_ops, vexpress_smp_init_ops will be called. > >> vexpress_smp_init_ops sets smp_ops to vexpress_smp_ops, that *break* > >> Xen. > > > > OK I see. > > > >> With this patch, xen_smp_init will be called instead of > >> vexpress_smp_init_ops, and smp_ops will be set to psci_smp_ops, > >> therefore *unbreaking* Xen. > > > > However that breaks MCPM. > > You mean on bare metal, right? For the bare metal, "xen,xen" property > would not be present and xen_smp_init is not used. So the vexpress MCPM > ops will be used. Aren't Dom0 cpu's basically virtual cpus? If Xen ever > needs the MCPM support, the Xen hook itself can figure out whether to > use MCPM support.
Well, if Xen has its own mdesc distinct from the VExpress one then things are indeed fine. Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
