x86/mb: remove module

The mb module has never been well defined, and has become irrelevant now
that the kern/atomic module has been introduced. Phase it out until the
need for non-SMP memory barriers rises.

5 files changed, 0 insertions, 73 deletions

diff --git a/arch/x86/Makefrag.am b/arch/x86/Makefrag.am
index 5bedee07..eb140bc6 100644
--- a/arch/x86/Makefrag.am
+++ b/arch/x86/Makefrag.am
@@ -43,7 +43,6 @@ x15_SOURCES +=                          \
         arch/x86/machine/io.h           \
         arch/x86/machine/lapic.c        \
         arch/x86/machine/lapic.h        \
-        arch/x86/machine/mb.h           \
         arch/x86/machine/multiboot.h    \
         arch/x86/machine/param.h        \
         arch/x86/machine/pic.c          \
diff --git a/arch/x86/machine/cpu.c b/arch/x86/machine/cpu.c
index 261e586e..ff860ba0 100644
--- a/arch/x86/machine/cpu.c
+++ b/arch/x86/machine/cpu.c
@@ -34,7 +34,6 @@
 #include <machine/cpu.h>
 #include <machine/io.h>
 #include <machine/lapic.h>
-#include <machine/mb.h>
 #include <machine/pmap.h>
 #include <machine/trap.h>
 #include <vm/vm_page.h>
diff --git a/arch/x86/machine/mb.h b/arch/x86/machine/mb.h
deleted file mode 100644
index 9fbd74bc..00000000
--- a/arch/x86/machine/mb.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright (c) 2012, 2013 Richard Braun.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *
- * Memory barriers.
- *
- * Keep in mind that memory barriers only act on the ordering of loads and
- * stores between internal processor queues and their caches. In particular,
- * it doesn't imply a store is complete after the barrier has completed, only
- * that other processors will see a new value thanks to the cache coherency
- * protocol. Memory barriers alone aren't suitable for device communication.
- *
- * The x86 architectural memory model (total-store ordering) already enforces
- * strong ordering for almost every access. The only exception is that stores
- * can be reordered after loads. As a result, load and store memory barriers
- * are simple compiler barriers whereas full memory barriers must generate
- * a barrier instruction.
- */
-
-#ifndef _X86_MB_H
-#define _X86_MB_H
-
-#include <kern/macros.h>
-
-#ifdef __LP64__
-
-static inline void
-mb_sync(void)
-{
-    asm volatile("mfence" : : : "memory");
-}
-
-#else /* __LP64__ */
-
-static inline void
-mb_sync(void)
-{
-    asm volatile("lock addl $0, 0(%%esp)" : : : "memory");
-}
-
-#endif /* __LP64__ */
-
-static inline void
-mb_load(void)
-{
-    barrier();
-}
-
-static inline void
-mb_store(void)
-{
-    barrier();
-}
-
-#endif /* _X86_MB_H */
diff --git a/doc/intro.9.txt b/doc/intro.9.txt
index c53f65f1..afac8e1c 100644
--- a/doc/intro.9.txt
+++ b/doc/intro.9.txt
@@ -152,8 +152,6 @@ module:kern/atomic::
   Inter-processor atomic operations.
 module:kern/cpumap::
   Specialized bitmaps representing processor sets.
-module:arch/mb::
-  Inter-processor memory barriers.
 module:kern/percpu::
   Per-processor data.
 module:kern/spinlock::
diff --git a/kern/llsync.h b/kern/llsync.h
index e95ed8c1..6736d6f9 100644
--- a/kern/llsync.h
+++ b/kern/llsync.h
@@ -77,7 +77,6 @@
 #include <kern/llsync_i.h>
 #include <kern/thread.h>
 #include <kern/work.h>
-#include <machine/mb.h>
 
 /*
  * Safely assign a pointer.