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x86: Initialise FPU regs during thread creation for eager FPU sharing 

When "eager FPU sharing" mode is enabled, FPU registers must be
initialised at the time of thread creation because the floating-point
context is always active and no further FPU initialisation is performed
later.

Note that, in case of the "lazy FPU sharing" mode, floating-point
context is inactive by default and the FPU is initialised when the
first floating-point instruction is executed.

Refer to the issue #44902 for more details.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
(cherry picked from commit f9a3f02b86)
This commit is contained in:
Stephanos Ioannidis 2022-04-16 01:55:43 +09:00 committed by Carles Cufí
parent 8f2d164674
commit b98ec9e0db
1 changed files with 14 additions and 0 deletions
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14
arch/x86/core/ia32/thread.c
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@ -114,4 +114,18 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
thread->arch.excNestCount = 0;
#endif /* CONFIG_LAZY_FPU_SHARING */
thread->arch.flags = 0;
/*
* When "eager FPU sharing" mode is enabled, FPU registers must be
* initialised at the time of thread creation because the floating-point
* context is always active and no further FPU initialisation is performed
* later.
*/
#if defined(CONFIG_EAGER_FPU_SHARING)
thread->arch.preempFloatReg.floatRegsUnion.fpRegs.fcw = 0x037f;
thread->arch.preempFloatReg.floatRegsUnion.fpRegs.ftw = 0xffff;
#if defined(CONFIG_X86_SSE)
thread->arch.preempFloatReg.floatRegsUnion.fpRegsEx.mxcsr = 0x1f80;
#endif /* CONFIG_X86_SSE */
#endif /* CONFIG_EAGER_FPU_SHARING */
}