Documentation/ABI/testing/sysfs-bus-event_source-devices-rdpmc

File Facts

System

Linux kernel

Corpus path

Documentation/ABI/testing/sysfs-bus-event_source-devices-rdpmc

Extension

[no extension]

Size

2218 bytes

Lines

45

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

What:           /sys/bus/event_source/devices/cpu.../rdpmc
Date:           November 2011
KernelVersion:  3.10
Contact:        Linux kernel mailing list linux-kernel@vger.kernel.org
Description:    The /sys/bus/event_source/devices/cpu.../rdpmc attribute
                is used to show/manage if rdpmc instruction can be
                executed in user space. This attribute supports 3 numbers.
                - rdpmc = 0
                user space rdpmc is globally disabled for all PMU
                counters.
                - rdpmc = 1
                user space rdpmc is globally enabled only in event mmap
                ioctl called time window. If the mmap region is unmapped,
                user space rdpmc is disabled again.
                - rdpmc = 2
                user space rdpmc is globally enabled for all PMU
                counters.

                In the Intel platforms supporting counter level's user
                space rdpmc disable feature (CPUID.23H.EBX[2] = 1), the
                meaning of 3 numbers is extended to
                - rdpmc = 0
                global user space rdpmc and counter level's user space
                rdpmc of all counters are both disabled.
                - rdpmc = 1
                No changes on behavior of global user space rdpmc.
                counter level's rdpmc of system-wide events is disabled
                but counter level's rdpmc of non-system-wide events is
                enabled.
                - rdpmc = 2
                global user space rdpmc and counter level's user space
                rdpmc of all counters are both enabled unconditionally.

                The default value of rdpmc is 1.

                Please notice:
                - global user space rdpmc's behavior would change
                immediately along with the rdpmc value's change,
                but the behavior of counter level's user space rdpmc
                won't take effect immediately until the event is
                reactivated or recreated.
                - The rdpmc attribute is global, even for x86 hybrid
                platforms. For example, changing cpu_core/rdpmc will
                also change cpu_atom/rdpmc.

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.