On Tue, Sep 01, 2015 at 10:29:12PM -0500, Scott Wood wrote: > On Wed, 2015-09-02 at 08:07 +0530, Ananth N Mavinakayanahalli wrote: > > On Tue, Sep 01, 2015 at 07:03:12PM -0500, Scott Wood wrote: > > > On Tue, 2015-09-01 at 12:11 +0530, Ananth N Mavinakayanahalli wrote: > > > > On Mon, Aug 31, 2015 at 08:35:17PM +1000, Michael Ellerman wrote: > > > > > On Tue, 2015-25-08 at 05:41:10 UTC, Ananth N Mavinakayanahalli wrote:
... > > > > We could certainly make this a generic config option.. but I am yet to > > > > see a real usecase outside of the KVM thingy. We do use TIF_UPROBE for > > > > something very similar, though that needs to fire much before the > > > > outstanding signals get handled. The user-return notifier is the last > > > > thing executed before return to userspace -- the two cannot be merged. > > > > > > > > Ananth > > > > > > > > PS: I am not sure having an 'ok' against the Documentation/features/ for > > > > powerpc is a valid enough argument for this :-) > > > > > > So how did you test this? What platforms did you test it on? What > > > hardware > > > support does it need? > > > > Simple kernel module below... Its fairly evident from the patch that the > > feature is a software only construct and no specific hardware support is > > needed. > > It's evident now that I'm aware of what the purpose is... It wasn't 100% > > clear before, at least from a quick glance, given that the explanation was > > "look at this hardware-specific KVM patch", whether there was an assumption > of something else going on -- and even things that are implemented in > software often work differently on book3s versus book3e, ppc32 versus ppc64, > etc. I meant the infrastructure is agnostic of the underlying Power platform. Sorry if I wasn't clear. > Why is this selected by KVM on PPC if KVM on PPC doesn't use it? What is the > user you're trying to enable? I copied Paul and Gautham to get their thoughts on whether it is something they could use on Power. At this time, apart from enabling the feature, I do not have a specific usecase for it. We can park this patch pending a real user on powerpc. > Where is the "profiler" that Documentation/features/debug/user-ret- > profiler/arch-support.txt hints at? I guess profiler is a misnomer. Not sure why it was named that and not a notifier. Ananth _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
