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CONFIG_EAGER_FP_SHARING¶
(No prompt – not directly user assignable.)
Type: bool
Help¶
This hidden option unconditionally saves/restores the FPU/SIMD register state on every context switch.
Mitigates CVE-2018-3665, but incurs a performance hit.
For vulnerable systems that process sensitive information in the FPU register set, should be used any time CONFIG_FLOAT is enabled, regardless if the FPU is used by one thread or multiple.
Direct dependencies¶
FLOAT && USERSPACE && CPU_HAS_FPU && X86
(Includes any dependencies from if’s and menus.)
Defaults¶
- “y” if !
X86_NO_LAZY_FP&&FLOAT&&USERSPACE&&CPU_HAS_FPU&&X86
Kconfig definition¶
At arch/x86/Kconfig:182
Included via Kconfig:10 → Kconfig.zephyr:29 → arch/Kconfig:15
Menu path: (top menu) → X86 Architecture Options → Processor Capabilities → Architecture Floating Point Options
config EAGER_FP_SHARING
bool
default "y" if !X86_NO_LAZY_FP && FLOAT && USERSPACE && CPU_HAS_FPU && X86
depends on FLOAT && USERSPACE && CPU_HAS_FPU && X86
help
This hidden option unconditionally saves/restores the FPU/SIMD
register state on every context switch.
Mitigates CVE-2018-3665, but incurs a performance hit.
For vulnerable systems that process sensitive information in the
FPU register set, should be used any time CONFIG_FLOAT is
enabled, regardless if the FPU is used by one thread or multiple.
(Definitions include propagated dependencies, including from if’s and menus.)