Settimeofday2

Settimeofday2 is a name used in some experimental or documentation contexts to describe an extended interface for setting the system clock, designed as a successor or augmentation to the traditional settimeofday mechanism. It is described as providing higher precision, more explicit time source selection, and better alignment with modern time APIs, while remaining callable from user space with appropriate privileges.

The exact public interface for settimeofday2 varies in drafts and experimental implementations, but common design goals include accepting a high-resolution time value and an optional specification of the time source. In many proposals, a signature is described as taking a time value (often in a timespec or equivalent structure) along with an optional time source or flags parameter to indicate how the adjustment should be applied (manual, network-synchronized, or a hybrid mode). Proposals emphasize backward compatibility with settimeofday through a compatible return model and errno-style error reporting.

Privileges and behavior are typically modeled after settimeofday: modifying the system clock generally requires elevated privileges (for example, a capability like CAP_SYS_TIME or root). On success, the interface would update the kernel’s real-time clock and, depending on flags, may trigger further synchronization or logging of the adjustment. On failure, a negative return value is reported and an errno indicates the reason (such as EPERM, EINVAL, or EFAULT).

Status and adoption vary by platform. Settimeofday2 remains a topic in discussions about timekeeping interfaces and is not part of standard, widely released kernels. It appears in some experimental branches and documentation but has no universally adopted, cross-platform specification. See also settimeofday, clock_settime, and timespec.