proc.5: Improve description of the KernelPageSize and MMUPageSize 'smaps' fields

Rework the text, make it clearer that MMUPageSize is a separate
line, add kernel version numbers, and example output.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man5/proc.5 b/man5/proc.5
index efd15e6fff51edf42c2852f60089d89768869666..a7b56e2ef1f0c57960e0b76104f91fbf1838db34 100644 (file)
--- a/man5/proc.5
+++ b/man5/proc.5
@@ -1658,6 +1658,8 @@ ShmemPmdMapped:        0 kB
 Swap:                  0 kB
 KernelPageSize:        4 kB
 MMUPageSize:           4 kB
+KernelPageSize:        4 kB
+MMUPageSize:           4 kB
 Locked:                0 kB
 VmFlags: rd ex mr mw me dw
 
@@ -1678,13 +1680,15 @@ that does not belong to any file.
 "Swap" shows how much
 would-be-anonymous memory is also used, but out on swap.
 
-The "KernelPageSize" entry is the page size used by the kernel to back a VMA.
+The "KernelPageSize" line (available since Linux 2.6.29)
+is the page size used by the kernel to back the virtual memory area.
 This matches the size used by the MMU in the majority of cases.
 However, one counter-example occurs on PPC64 kernels
-whereby a kernel using 64K as a base page size may still use 4K
+whereby a kernel using 64kB as a base page size may still use 4kB
 pages for the MMU on older processors.
-To distinguish, this
-patch reports "MMUPageSize" as the page size used by the MMU.
+To distinguish the two attributes, the "MMUPageSize" line
+(also available since Linux 2.6.29)
+reports the page size used by the MMU.
 
 The "Locked" indicates whether the mapping is locked in memory
 or not.