Function fpuinit

freebsd/amd64/amd64/fpu.c:393–426

* Initialize the floating point unit. */

 * Initialize the floating point unit.
 */
void
fpuinit(void)
{
	register_t saveintr;
	u_int mxcsr;
	u_short control;

	if (IS_BSP())
		fpuinit_bsp1();

	if (use_xsave) {
		load_cr4(rcr4() | CR4_XSAVE);
		load_xcr(XCR0, xsave_mask);
	}

	/*
	 * XCR0 shall be set up before CPU can report the save area size.
	 */
	if (IS_BSP())
		fpuinit_bsp2();

	/*
	 * It is too early for critical_enter() to work on AP.
	 */
	saveintr = intr_disable();
	stop_emulating();
	fninit();
	control = __INITIAL_FPUCW__;
	fldcw(control);
	mxcsr = __INITIAL_MXCSR__;
	ldmxcsr(mxcsr);
	start_emulating();
	intr_restore(saveintr);
}

/*
 * On the boot CPU we generate a clean state that is used to