Augustin Cavalier
4c76039f6f
This reverts most ofc7360f4b02. Unlike the other floating-point registers, these values are callee-saved (see "System V Application Binary Interface, AMD64 Architecture Supplement" section 3.2.1.) So we need to preserve their values and not reset defaults on context switch. EMMS, as the previous changes used, does not suffice to clear exceptions. We could use FNCLEX instead, but we need to reset x87 state on context switch anyway, so use FNINIT. Do not reinstate FNCLEX in the exception handler since it will be executed on context switch anyway. We also need to ensure a clean initial state, so take care of that in arch_thread_init. See also: * remarks in396b74228e* as well as53e2dc0f85Fixes #19454 and #18624. Doesn't regress #18656 and #19063. Doesn't seem to affect #19450. Change-Id: I7179f1ec7304e7aed09ff80f6773e53d5dbdf5f9 Reviewed-on: https://review.haiku-os.org/c/haiku/+/9081 Reviewed-by: Jérôme Duval <[email protected]> Tested-by: Commit checker robot <[email protected]> Reviewed-by: waddlesplash <[email protected]>