On Tue, Jul 26, 2022 at 06:17:18PM +0530, Abhishek Sahu wrote: > Thanks Alex for your thorough review of uAPI. > I have incorporated all the suggestions. > Following is the updated uAPI. > > /* > * Upon VFIO_DEVICE_FEATURE_SET, allow the device to be moved into a low power > * state with the platform-based power management. Device use of lower power > * states depends on factors managed by the runtime power management core, > * including system level support and coordinating support among dependent > * devices. Enabling device low power entry does not guarantee lower power > * usage by the device, nor is a mechanism provided through this feature to > * know the current power state of the device. If any device access happens > * (either from the host or through the vfio uAPI) when the device is in the > * low power state, then the host will move the device out of the low power > * state as necessary prior to the access. Once the access is completed, the > * device may re-enter the low power state. For single shot low power support > * with wake-up notification, see > * VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY_WITH_WAKEUP below. Access to mmap'd > * device regions is disabled on LOW_POWER_ENTRY and may only be resumed after > * calling LOW_POWER_EXIT. > */ > #define VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY 3 > > /* > * This device feature has the same behavior as > * VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY with the exception that the user > * provides an eventfd for wake-up notification. It feels like this should be one entry point instead of two. A flag "automatic re-sleep" and an optional eventfd (-1 means not provided) seems to capture both of these behaviors in a bit clearer and extendable way. Jason
