Documentation/virt/kvm/arm/ptp_kvm.rst
Source file repositories/reference/linux-study-clean/Documentation/virt/kvm/arm/ptp_kvm.rst
File Facts
- System
- Linux kernel
- Corpus path
Documentation/virt/kvm/arm/ptp_kvm.rst- Extension
.rst- Size
- 2069 bytes
- Lines
- 36
- Domain
- Support Tooling And Documentation
- Bucket
- Documentation
- Inferred role
- Support Tooling And Documentation: documentation
- Status
- atlas-only
Why This File Exists
Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
- Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
Dependency Surface
- No C-style include directives detected by the generator.
Detected Declarations
- No top-level syscall, struct, function, initcall, or export declaration detected by the generator.
Annotated Snippet
.. SPDX-License-Identifier: GPL-2.0
PTP_KVM support for arm/arm64
=============================
PTP_KVM is used for high precision time sync between host and guests.
It relies on transferring the wall clock and counter value from the
host to the guest using a KVM-specific hypercall.
``ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID``
----------------------------------------
Retrieve current time information for the specific counter. There are no
endianness restrictions.
+---------------------+-------------------------------------------------------+
| Presence: | Optional |
+---------------------+-------------------------------------------------------+
| Calling convention: | HVC32 |
+---------------------+----------+--------------------------------------------+
| Function ID: | (uint32) | 0x86000001 |
+---------------------+----------+----+---------------------------------------+
| Arguments: | (uint32) | R1 | ``KVM_PTP_VIRT_COUNTER (0)`` |
| | | +---------------------------------------+
| | | | ``KVM_PTP_PHYS_COUNTER (1)`` |
+---------------------+----------+----+---------------------------------------+
| Return Values: | (int32) | R0 | ``NOT_SUPPORTED (-1)`` on error, else |
| | | | upper 32 bits of wall clock time |
| +----------+----+---------------------------------------+
| | (uint32) | R1 | Lower 32 bits of wall clock time |
| +----------+----+---------------------------------------+
| | (uint32) | R2 | Upper 32 bits of counter |
| +----------+----+---------------------------------------+
| | (uint32) | R3 | Lower 32 bits of counter |
+---------------------+----------+----+---------------------------------------+Annotation
- Atlas domain: Support Tooling And Documentation / Documentation.
- Implementation status: atlas-only.
Implementation Notes
- This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
- Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
- Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.