[PATCH v4 5/7] powerpc/fadump: Update documentation to reflect CMA reservation.

[Mahesh J Salgaonkar]

From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
---
 Documentation/powerpc/firmware-assisted-dump.txt |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/powerpc/firmware-assisted-dump.txt b/Documentation/powerpc/firmware-assisted-dump.txt
index 30b32f879219..2ab13270b050 100644
--- a/Documentation/powerpc/firmware-assisted-dump.txt
+++ b/Documentation/powerpc/firmware-assisted-dump.txt
@@ -113,7 +113,15 @@ header, is usually reserved at an offset greater than boot memory
 size (see Fig. 1). This area is *not* released: this region will
 be kept permanently reserved, so that it can act as a receptacle
 for a copy of the boot memory content in addition to CPU state
-and HPTE region, in the case a crash does occur.
+and HPTE region, in the case a crash does occur. Since this reserved
+memory area is used only after the system crash, there is no point in
+blocking this significant chunk of memory from production kernel.
+Hence, the implementation uses the Linux kernel's Contiguous Memory
+Allocator (CMA) for memory reservation. With CMA reservation this memory
+will be available for applications to use it, while kernel is prevented
+from using it. With this fadump will still be able to capture all of
+the kernel memory and most of the user space memory except the user
+pages that were present in CMA region.
 
 The first kernel, during fadump registration, prepares ELF core header
 that contains necessary information for the coredump of the 1st kernel