The represents the saved context of a processor's floating-point unit (FPU), as well as its extended vector registers (such as Intel AVX-512, Intel AMX, or ARM NEON/SVE). Because these architectural registers are massive—storing hundreds or thousands of bits per register—saving and restoring them during a context switch is resource-intensive.
The modern standard for saving extensive register states (including AVX and AVX-512) to prevent register corruption across context switches. Where Does "VSO" Come In?
To fully appreciate Pin’s FPSTATE , it is helpful to compare it with a similar yet distinct concept in the Linux kernel: the . The kernel uses its own fpstate and fpu structures to manage the FPU context during task switching. For a running process, the kernel saves the current FPU state into a task-specific fpstate buffer. However, this kernel structure is private and not directly accessible from user space. Pin’s FPSTATE serves a parallel but distinct purpose: it provides a user-space abstraction of this same hardware state, allowing instrumentation tools to intercept and analyze it before the kernel saves or restores it. fpstate vso
Linux uses XSAVEC (if available) for compacted FPState saving. The kernel no longer uses lazy FPU switching by default; it eagerly saves with optimization.
Tracked by the kernel but directly altered by userspace assembly instructions. The represents the saved context of a processor's
very superior old. usually used of brandy 12 to 17 years old. Merriam-Webster FPState - NI - National Instruments
By integrating VSO.ai into their existing VCS regression environment without modifying their design or testbench code, they achieved: Where Does "VSO" Come In
If you see xstate_size larger than your kernel stack size, VSO is likely active.
In traditional computing environments, when the operating system switches between processes, it saves and restores the FPSTATE to ensure continuity. However, in virtualized environments, this process becomes more complex due to the additional layer of abstraction introduced by the hypervisor (the software that creates and manages VMs).
#include "pin.H" #include <iostream> #include <iomanip>