CONFIG_LAZY_FPU_SHARING

(No prompt – not directly user assignable.)

Type: bool

Help

This hidden option allows multiple threads to use the floating point
registers, using logic to lazily save/restore the floating point
register state on context switch.

On Intel Core processors, may be vulnerable to exploits which allows
malware to read the contents of all floating point registers, see
CVE-2018-3665.

Direct dependencies

FPU && !EAGER_FPU_SHARING && FPU_SHARING && CPU_HAS_FPU && !X86_64 && X86

(Includes any dependencies from ifs and menus.)

Default

• y if X86_NO_LAZY_FP || !USERSPACE

Kconfig definition

At <Zephyr Architecture>/x86/core/Kconfig.ia32:121

Included via Kconfig:8 → Kconfig.zephyr:39 → <Zephyr Architecture>/Kconfig:12 → <Zephyr Architecture>/x86/Kconfig:482

Menu path: (Top) → X86 Architecture Options → Processor Capabilities → Architecture Floating Point Options

config LAZY_FPU_SHARING
    bool
    default y if X86_NO_LAZY_FP || !USERSPACE
    depends on FPU && !EAGER_FPU_SHARING && FPU_SHARING && CPU_HAS_FPU && !X86_64 && X86
    help
      This hidden option allows multiple threads to use the floating point
      registers, using logic to lazily save/restore the floating point
      register state on context switch.

      On Intel Core processors, may be vulnerable to exploits which allows
      malware to read the contents of all floating point registers, see
      CVE-2018-3665.

(The ‘depends on’ condition includes propagated dependencies from ifs and menus.)