[src/trunk]: src/sys/arch/x86/x86 Remove this #undef on native amd64, but kee...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fa2d112b2c8d
branches:  trunk
changeset: 827121:fa2d112b2c8d
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Oct 15 11:39:42 2017 +0000

description:
Remove this #undef on native amd64, but keep it on Xen.

diffstat:

 sys/arch/x86/x86/sys_machdep.c |  24 ++++--------------------
 1 files changed, 4 insertions(+), 20 deletions(-)

diffs (52 lines):

diff -r 154514df4c23 -r fa2d112b2c8d sys/arch/x86/x86/sys_machdep.c
--- a/sys/arch/x86/x86/sys_machdep.c    Sun Oct 15 11:36:15 2017 +0000
+++ b/sys/arch/x86/x86/sys_machdep.c    Sun Oct 15 11:39:42 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_machdep.c,v 1.39 2017/10/15 10:58:32 maxv Exp $    */
+/*     $NetBSD: sys_machdep.c,v 1.40 2017/10/15 11:39:42 maxv Exp $    */
 
 /*
  * Copyright (c) 1998, 2007, 2009, 2017 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_machdep.c,v 1.39 2017/10/15 10:58:32 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_machdep.c,v 1.40 2017/10/15 11:39:42 maxv Exp $");
 
 #include "opt_mtrr.h"
 #include "opt_pmc.h"
@@ -65,24 +65,7 @@
 #include <machine/mtrr.h>
 
 #ifdef __x86_64__
-/*
- * The code for USER_LDT on amd64 is mostly functional, but it is still not
- * enabled.
- *
- * On amd64 we are allowing only 8-byte-sized entries in the LDT, and we are
- * not allowing the user to overwrite the existing entries (below LDT_SIZE).
- * Note that USER_LDT is used only by 32bit applications, under compat_netbsd32.
- * This is theoretically enough for Wine to work.
- *
- * However, letting segment registers have different location breaks amd64's
- * Thread Local Storage: %fs and %gs must be reloaded when returning to
- * userland. See the tech-kern@ archive from February 2017. A patch has been
- * proposed to fix that, but Wine still randomly crashes; it is not clear
- * whether the issues come from Wine, from netbsd32 or from the patch itself.
- */
-#undef USER_LDT
-/* Need to be checked. */
-#undef IOPERM
+#undef IOPERM  /* not implemented */
 #else
 #if defined(XEN)
 #undef IOPERM
@@ -92,6 +75,7 @@
 #endif
 
 #ifdef XEN
+#undef USER_LDT
 #undef PMC
 #endif