handle kernelcore=: generic

This patch adds the kernelcore= parameter for x86.

Once all patches are applied, a new command-line parameter exist and a new
sysctl.  This patch adds the necessary documentation.

From: Yasunori Goto <y-goto@jp.fujitsu.com>

  When "kernelcore" boot option is specified, kernel can't boot up on ia64
  because of an infinite loop.  In addition, the parsing code can be handled
  in an architecture-independent manner.

  This patch uses common code to handle the kernelcore= parameter.  It is
  only available to architectures that support arch-independent zone-sizing
  (i.e.  define CONFIG_ARCH_POPULATES_NODE_MAP).  Other architectures will
  ignore the boot parameter.

[bunk@stusta.de: make cmdline_parse_kernelcore() static]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 8363ad3ba018..1794affbd06f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -817,6 +817,22 @@ and is between 256 and 4096 characters. It is defined in the file
         js=             [HW,JOY] Analog joystick
                         See Documentation/input/joystick.txt.
 
+        kernelcore=nn[KMG]      [KNL,IA-32,IA-64,PPC,X86-64] This parameter
+                        specifies the amount of memory usable by the kernel
+                        for non-movable allocations.  The requested amount is
+                        spread evenly throughout all nodes in the system. The
+                        remaining memory in each node is used for Movable
+                        pages. In the event, a node is too small to have both
+                        kernelcore and Movable pages, kernelcore pages will
+                        take priority and other nodes will have a larger number
+                        of kernelcore pages.  The Movable zone is used for the
+                        allocation of pages that may be reclaimed or moved
+                        by the page migration subsystem.  This means that
+                        HugeTLB pages may not be allocated from this zone.
+                        Note that allocations like PTEs-from-HighMem still
+                        use the HighMem zone if it exists, and the Normal
+                        zone if it does not.
+
         keepinitrd      [HW,ARM]
 
         kstack=N        [IA-32,X86-64] Print N words from the kernel stack