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From: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
To: linuxppc-dev <linuxppc-dev@ozlabs.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	kernelfans@gmail.com,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Ananth Narayan <ananth@in.ibm.com>,
	Hari Bathini <hbathini@linux.vnet.ibm.com>,
	Nathan Fontenot <nfont@linux.vnet.ibm.com>,
	Anshuman Khandual <khandual@linux.vnet.ibm.com>
Subject: [PATCH v4 5/7] powerpc/fadump: Update documentation to reflect CMA reservation.
Date: Fri, 20 Apr 2018 10:34:51 +0530	[thread overview]
Message-ID: <152420069171.31037.10578740903757971568.stgit@jupiter.in.ibm.com> (raw)
In-Reply-To: <152420062000.31037.770773018944092449.stgit@jupiter.in.ibm.com>

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

Signed-off-by: Mahesh Salgaonkar <mahesh@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

  parent reply	other threads:[~2018-04-20  5:06 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20  5:04 [PATCH v4 0/7] powerpc/fadump: Improvements and fixes for firmware-assisted dump Mahesh J Salgaonkar
2018-04-20  5:04 ` [PATCH v4 1/7] powerpc/fadump: Move the metadata region to start of the reserved area Mahesh J Salgaonkar
2018-04-22  1:58   ` Nicholas Piggin
2018-04-23  5:16     ` Mahesh Jagannath Salgaonkar
2018-04-20  5:04 ` [PATCH v4 2/7] powerpc/fadump: Update documentation to reflect the metadata region movement Mahesh J Salgaonkar
2018-04-20  5:04 ` [PATCH v4 3/7] powerpc/fadump: un-register fadump on kexec path Mahesh J Salgaonkar
2018-04-22  1:58   ` Nicholas Piggin
2018-04-23  5:17     ` Mahesh Jagannath Salgaonkar
2018-04-20  5:04 ` [PATCH v4 4/7] powerpc/fadump: Reservationless firmware assisted dump Mahesh J Salgaonkar
2018-04-23 12:53   ` Hari Bathini
2018-04-20  5:04 ` Mahesh J Salgaonkar [this message]
2018-04-20  5:05 ` [PATCH v4 6/7] powerpc/fadump: throw proper error message on fadump registration failure Mahesh J Salgaonkar
2018-04-20  5:05 ` [PATCH v4 7/7] powerpc/fadump: Do not allow hot-remove memory from fadump reserved area Mahesh J Salgaonkar

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