On 07/24/2017 01:07 PM, Benjamin Herrenschmidt wrote: > On Mon, 2017-07-24 at 19:50 +1000, David Gibson wrote: >> On Mon, Jul 24, 2017 at 05:00:57PM +1000, Benjamin Herrenschmidt wrote: >>> On Mon, 2017-07-24 at 14:36 +1000, David Gibson wrote: >>>> On Wed, Jul 05, 2017 at 07:13:21PM +0200, Cédric Le Goater wrote: >>>>> These flags define some characteristics of the source : >>>>> >>>>> - XIVE_SRC_H_INT_ESB the Event State Buffer are controlled with a >>>>> specific hcall H_INT_ESB >>>> >>>> What's the other option? >>> >>> Direct MMIO access. Normally all interrupts use normal MMIOs, >>> each interrupts has an associated MMIO page with special MMIOs >>> to control the source state (PQ bits). This is something I added >>> to the PAPR spec (and the OPAL <-> Linux interface) to allow firmware >>> to work around broken HW (which happens on some P9 versions). >> >> Ok.. and that's something that can be decided at runtime? > > Well, at this point I think nothing will set that flag.... It's there > for workaround around HW bugs on some chips. At least in full emu it > shouldn't happen unless we try to emulate those bugs. Hopefully direct > MMIO will just work.
Nevertheless I have added support for the hcall in Linux and QEMU. To use, I think we could create a specific source. C.
