From ef209971e9aaeefde0d7caa90efcb5343aaf3fe0 Mon Sep 17 00:00:00 2001
From: Bruce Evans <bde@FreeBSD.org>
Date: Mon, 29 Aug 2016 14:38:31 +0000
Subject: [PATCH] Shorten banal comments about zeroing and copying pages. 
 Don't give implementation details that last echoed the code 15-20 years ago.
 But add a detail about pagezero() on i386.  Switch from Mach style to BSD
 style.

---
 sys/amd64/amd64/pmap.c | 21 +++++++--------------
 sys/i386/i386/pmap.c   | 24 ++++++++++--------------
 2 files changed, 17 insertions(+), 28 deletions(-)

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 3cb85301e93f..104815908bc2 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -5153,8 +5153,7 @@ out:
 }
 
 /*
- *	pmap_zero_page zeros the specified hardware page by mapping
- *	the page into KVM and using bzero to clear its contents.
+ * Zero the specified hardware page.
  */
 void
 pmap_zero_page(vm_page_t m)
@@ -5165,10 +5164,8 @@ pmap_zero_page(vm_page_t m)
 }
 
 /*
- *	pmap_zero_page_area zeros the specified hardware page by mapping 
- *	the page into KVM and using bzero to clear its contents.
- *
- *	off and size may not cover an area beyond a single hardware page.
+ * Zero an an area within a single hardware page.  off and size must not
+ * cover an area beyond a single hardware page.
  */
 void
 pmap_zero_page_area(vm_page_t m, int off, int size)
@@ -5182,10 +5179,9 @@ pmap_zero_page_area(vm_page_t m, int off, int size)
 }
 
 /*
- *	pmap_zero_page_idle zeros the specified hardware page by mapping 
- *	the page into KVM and using bzero to clear its contents.  This
- *	is intended to be called from the vm_pagezero process only and
- *	outside of Giant.
+ * Zero the specified hardware page in a way that minimizes cache thrashing.
+ * This is intended to be called from the vm_pagezero process only and
+ * outside of Giant.
  */
 void
 pmap_zero_page_idle(vm_page_t m)
@@ -5196,10 +5192,7 @@ pmap_zero_page_idle(vm_page_t m)
 }
 
 /*
- *	pmap_copy_page copies the specified (machine independent)
- *	page by mapping the page into virtual memory and using
- *	bcopy to copy the page, one machine dependent page at a
- *	time.
+ * Copy 1 specified hardware page to another.
  */
 void
 pmap_copy_page(vm_page_t msrc, vm_page_t mdst)
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index d40de0ff8b10..d08c28babc00 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -4174,6 +4174,9 @@ out:
 	PMAP_UNLOCK(dst_pmap);
 }	
 
+/*
+ * Zero 1 page of virtual memory mapped from a hardware page by the caller.
+ */
 static __inline void
 pagezero(void *page)
 {
@@ -4191,8 +4194,7 @@ pagezero(void *page)
 }
 
 /*
- *	pmap_zero_page zeros the specified hardware page by mapping 
- *	the page into KVM and using bzero to clear its contents.
+ * Zero the specified hardware page.
  */
 void
 pmap_zero_page(vm_page_t m)
@@ -4214,10 +4216,8 @@ pmap_zero_page(vm_page_t m)
 }
 
 /*
- *	pmap_zero_page_area zeros the specified hardware page by mapping 
- *	the page into KVM and using bzero to clear its contents.
- *
- *	off and size may not cover an area beyond a single hardware page.
+ * Zero an an area within a single hardware page.  off and size must not
+ * cover an area beyond a single hardware page.
  */
 void
 pmap_zero_page_area(vm_page_t m, int off, int size)
@@ -4242,10 +4242,9 @@ pmap_zero_page_area(vm_page_t m, int off, int size)
 }
 
 /*
- *	pmap_zero_page_idle zeros the specified hardware page by mapping 
- *	the page into KVM and using bzero to clear its contents.  This
- *	is intended to be called from the vm_pagezero process only and
- *	outside of Giant.
+ * Zero the specified hardware page in a way that minimizes cache thrashing.
+ * This is intended to be called from the vm_pagezero process only and
+ * outside of Giant.
  */
 void
 pmap_zero_page_idle(vm_page_t m)
@@ -4263,10 +4262,7 @@ pmap_zero_page_idle(vm_page_t m)
 }
 
 /*
- *	pmap_copy_page copies the specified (machine independent)
- *	page by mapping the page into virtual memory and using
- *	bcopy to copy the page, one machine dependent page at a
- *	time.
+ * Copy 1 specified hardware page to another.
  */
 void
 pmap_copy_page(vm_page_t src, vm_page_t dst)