kexec: make extended crashkernel= syntax less confusing

The extended crashkernel syntax is a little confusing in the way it handles
ranges.  eg:

 crashkernel=512M-2G:64M,2G-:128M

Means if the machine has between 512M and 2G of memory the crash region should
be 64M, and if the machine has 2G of memory the region should be 64M.  Only if
the machine has more than 2G memory will 128M be allocated.

Although that semantic is correct, it is somewhat baffling.  Instead I propose
that the end of the range means the first address past the end of the range,
ie: 512M up to but not including 2G.

[bwalle@suse.de: clarify inclusive/exclusive in crashkernel commandline in documentation]
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Bernhard Walle <bwalle@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index d0ac72cc19ff8e29667e7a2c58e21d2d0cfafcb5..b8e52c0355d3bab81760adbf62d0c8a06a9ba52a 100644 (file)
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -245,6 +245,8 @@ The syntax is:
     crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
     range=start-[end]
 
+    'start' is inclusive and 'end' is exclusive.
+
 For example:
 
     crashkernel=512M-2G:64M,2G-:128M
@@ -253,10 +255,11 @@ This would mean:
 
     1) if the RAM is smaller than 512M, then don't reserve anything
        (this is the "rescue" case)
-    2) if the RAM size is between 512M and 2G, then reserve 64M
+    2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
     3) if the RAM size is larger than 2G, then reserve 128M
 
 
+
 Boot into System Kernel
 =======================
 

diff --git a/kernel/kexec.c b/kernel/kexec.c
index cb85c79989b440a3979e3d2e6dd3bcfa198b1c3b..1c5fcacbcf336b8dc82d0b02202a3d95c32fbd13 100644 (file)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1217,7 +1217,7 @@ static int __init parse_crashkernel_mem(char                      *cmdline,
                }
 
                /* match ? */
-               if (system_ram >= start && system_ram <= end) {
+               if (system_ram >= start && system_ram < end) {
                        *crash_size = size;
                        break;
                }