svn commit: r348802 - head/sys/amd64/amd64

[Konstantin Belousov]

Author: kib
Date: Sat Jun  8 16:03:34 2019
New Revision: 348802
URL: https://svnweb.freebsd.org/changeset/base/348802

Log:
  Remove lazy FPU switch support from amd64.
  
  It is incompatible with some future features.
  
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/fpu.c

Modified: head/sys/amd64/amd64/fpu.c
==============================================================================
--- head/sys/amd64/amd64/fpu.c	Sat Jun  8 15:24:03 2019	(r348801)
+++ head/sys/amd64/amd64/fpu.c	Sat Jun  8 16:03:34 2019	(r348802)
@@ -154,11 +154,6 @@ static	void	fpu_clean_state(void);
 SYSCTL_INT(_hw, HW_FLOATINGPT, floatingpoint, CTLFLAG_RD,
     SYSCTL_NULL_INT_PTR, 1, "Floating point instructions executed in hardware");
 
-int lazy_fpu_switch = 0;
-SYSCTL_INT(_hw, OID_AUTO, lazy_fpu_switch, CTLFLAG_RWTUN | CTLFLAG_NOFETCH,
-    &lazy_fpu_switch, 0,
-    "Lazily load FPU context after context switch");
-
 int use_xsave;			/* non-static for cpu_switch.S */
 uint64_t xsave_mask;		/* the same */
 static	uma_zone_t fpu_save_area_zone;
@@ -269,7 +264,6 @@ fpuinit_bsp1(void)
 	uint64_t xsave_mask_user;
 	bool old_wp;
 
-	TUNABLE_INT_FETCH("hw.lazy_fpu_switch", &lazy_fpu_switch);
 	if (!use_xsave)
 		return;
 	cpuid_count(0xd, 0x0, cp);
@@ -774,8 +768,7 @@ void
 fpu_activate_sw(struct thread *td)
 {
 
-	if (lazy_fpu_switch || (td->td_pflags & TDP_KTHREAD) != 0 ||
-	    !PCB_USER_FPU(td->td_pcb)) {
+	if ((td->td_pflags & TDP_KTHREAD) != 0 || !PCB_USER_FPU(td->td_pcb)) {
 		PCPU_SET(fpcurthread, NULL);
 		start_emulating();
 	} else if (PCPU_GET(fpcurthread) != td) {