On Tue, Apr 10, 2012 at 02:03:05PM -0600, Alex Williamson wrote: > On Tue, 2012-04-10 at 22:36 +0300, Michael S. Tsirkin wrote: > > On Tue, Apr 10, 2012 at 12:29:09PM -0600, Alex Williamson wrote: > > > I never really intended the power state bitmap to be for power > > > management of any sort, I was trying to support this kind of event flow: > > > > > > http://www.microsoft.com/china/whdc/system/pnppwr/hotadd/hotplugpci.mspx#EYH > > > > > > Hot-add: > > > - Generate SCI > > > - _Lxx/_Exx method determines which slots to Notify > > > - _STA method for slots indicates device present > > > - _PS0 requests slot turned on > > > - _STA method reports device present & enabled > > > > > > Hot-remove: > > > - Generate SCI > > > - _Lxx/_Exx method determines which slots to Notify > > > - _PS3 powers off slot > > > - _EJ0 ejects device > > > - _STA verifies success > > > > > > _STA is generated using the "present" and "power" registers and _PSx > > > methods directly manipulate "power". We could then have some kind of > > > "info pcislot" command that allows querying slot state. Maybe there's > > > even an opportunity for unpowered slot surprise removal. In effect, the > > > "power" register tracks the "actual" state vs the "requested" state, but > > > if it's controlled by _PSx, it seems better to not try to do a > > > translation. > > > > > > Are there better models or event flows we should be aiming for? Thanks, > > > > > > Alex > > > > You already said exactly this and both me and Marcelo responded, no? > > Sorry, difficult to try to summarize a reply to a weekend+ of > conversation, is this better? > > On Sun, 2012-04-08 at 02:13 -0300, Marcelo Tosatti wrote: > On Wed, Apr 04, 2012 at 11:51:00PM -0600, Alex Williamson wrote: > > > > What problem are you trying to address by doing so? > > I'm trying to come up with a model that provides better event life > cycle, clear register ownership, and facilitates features like the event > flow in the msft link above. We can get away with asking the guest to > do extra device checks on slots, but it's a workaround for a broken > model. > > > What is the need for power control? Clearly there is no advantage in > > powering down a virtual device. > > In combination with the "present" register it allows emulating more _STA > states. > > On Sun, 2012-04-08 at 10:15 +0300, Michael S. Tsirkin wrote: > On Sun, Apr 08, 2012 at 02:13:00AM -0300, Marcelo Tosatti wrote: > > > What is the need for power control? Clearly there is no advantage in > > > powering down a virtual device. > > > > There probably are for an assigned device? > > That was not my intention > > [Skipping the rest since it's all headed in the direction of using the > power register to do some kind of chipset/device power control] > > If there was some decision or direction provided by the rest of the > thread, I missed it, please restate. Thanks, > > Alex
Some points I remember - power on is better called slot enabled - guests dont actually call _PSX like you want them to (PS3 for sure, in my testing PS0 too), and _EJ0 must remove power - populated slots after reset must be auto-enabled HTH
