Thanks Daniel and Joonas. : p See my replies below. > -----Original Message----- > From: daniel.vetter@xxxxxxxx [mailto:daniel.vetter@xxxxxxxx] On Behalf Of > Daniel Vetter > Sent: Monday, May 23, 2016 5:18 PM > To: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > Cc: Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; Vetter, Daniel > <daniel.vetter@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: Building GVT-g as a sub-module of i915 > > On Mon, May 23, 2016 at 4:16 PM, Joonas Lahtinen > <joonas.lahtinen@xxxxxxxxxxxxxxx> wrote: > > On ma, 2016-05-23 at 07:03 +0000, Wang, Zhi A wrote: > >> Hi Guys: > >> I'm trying to make GVT-g as a sub-module of i915 in the next > >> version patchset. The basic idea is to introduce a "gvt-g pre-enabled > >> state" in i915. I think it should be a kernel option. > >> > > > > Could not the GGTT partitioning be done ad hoc by moving objects out > > of the memory areas to be ballooned? This way gvt module could just be > > loaded and it would work, instead of having to reboot and change > > kernel parameters. > > Yeah, if we want to make gvt loadable, then it should indeed not reserve > anything if it's not loaded. Otherwise there's no point in that option, and it's no > better than just a static Kconfig+ maybe i915 module option. > > If dynamic loading is too hard for v1, then I'd say we should postpone it to > post-merging. GVT-g is already tricky to integrate as-is. > Yes. We can try to reserve some portion of GGTT by allocating 2 gem object and pin them into mappable / high GGTT memory. I think better we can postpone it to post-merging. For now statically partition only requires little changes. :) > >> When this kernel option is enabled by user, i915 will do GGTT > >> partition and save HW initial MMIO snapshot for gvt-g module during > >> loading. > > > > Like discussed in the F2F, I really think taking a MMIO snapshot in > > Dom0 at boot sounds a little suspicious to me as changing Dom0 BIOS > > settings could very obscurely break VM booting, especially if > > migration is at some point wanted. It will also leak the Dom0 boot > > state to a VM, which I do not like either. > > > > I would be more comfortable if the VMs are booting to a driver-fixed > > MMIO state. > > > > Any thoughts by others on these? > > Golden MMIO state sounds like a good idea. Yes. It's a good idea. I agree with that. But consider that each GT stepping/generation might need a dedicated MMIO snapshot. They could become huge, probably at the very beginning 2MB is OK, in future we should get them out of kernel. BTW: It's not only MMIO bar needs a snapshot, PCI configuration space also needs a golden snapshot. :) So consider the GT/SKUs we have, maybe we should figure out a way to store them at first. :) > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
