On Tue, 12 Mar 2024 13:51:27 +0000, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote: > > The upcoming PSCI v1.3 specification adds support for a SYSTEM_OFF2 Pointer to the spec? Crucially, this is in the Alpha state, meaning that it is still subject to change [1]. > function which is analogous to ACPI S4 state. This will allow hosting > environments to determine that a guest is hibernated rather than just > powered off, and ensure that they preserve the virtual environment > appropriately to allow the guest to resume safely (or bump the > hardware_signature in the FACS to trigger a clean reboot instead). > > This adds support for it to KVM, and to the guest hibernate code. > > Strictly, we should perhaps also allow the guest to detect PSCI v1.3, > but when v1.1 was added in commit 512865d83fd9 it was done > unconditionally, which seems wrong. Shouldn't we have a way for > userspace to control what gets exposed, rather than silently changing > the guest behaviour with newer host kernels? Should I add a > KVM_CAP_ARM_PSCI_VERSION? Do you mean something like 85bd0ba1ff98? M. [1] https://documentation-service.arm.com/static/65e59325837c4d065f6556a6 -- Without deviation from the norm, progress is not possible.
