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From: Jiri Bohac <jbohac@suse.cz>
To: Baoquan He <bhe@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
	Dave Young <dyoung@redhat.com>,
	kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, mhocko@suse.cz
Subject: [PATCH 4/4] kdump, documentation: describe craskernel CMA reservation
Date: Fri, 24 Nov 2023 20:58:25 +0100	[thread overview]
Message-ID: <ZWEAYdO7VfT02EJz@dwarf.suse.cz> (raw)
In-Reply-To: <ZWD_fAPqEWkFlEkM@dwarf.suse.cz>

Describe the new crashkernel ",cma" suffix in Documentation/

---
 Documentation/admin-guide/kdump/kdump.rst       | 10 ++++++++++
 Documentation/admin-guide/kernel-parameters.txt |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 5762e7477a0c..4ec08e5843dc 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -317,6 +317,16 @@ crashkernel syntax
 
             crashkernel=0,low
 
+4) crashkernel=size,cma
+
+   Reserves additional memory from CMA. A standard crashkernel reservation, as
+   described above, is still needed, but can be just small enough to hold the
+   kernel and initrd. All the memory the crash kernel needs for its runtime and
+   for running the kdump userspace processes can be provided by this CMA
+   reservation, re-using memory available to the production system's userspace.
+   Because of this re-using, the CMA reservation should not be used if it's
+   intended to dump userspce memory.
+
 Boot into System Kernel
 -----------------------
 1) Update the boot loader (such as grub, yaboot, or lilo) configuration
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 65731b060e3f..ee9fc40a97fd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -914,6 +914,13 @@
 			0: to disable low allocation.
 			It will be ignored when crashkernel=X,high is not used
 			or memory reserved is below 4G.
+	crashkernel=size[KMG],cma
+			[KNL, X86] Reserve additional crash kernel memory from CMA.
+			This reservation is usable by the 1st system's userspace,
+			so this should not be used if dumping of userspace 
+			memory is intended. A standard crashkernel reservation, 
+			as described above, is still needed to hold the crash 
+			kernel and initrd. 
 
 	cryptomgr.notests
 			[KNL] Disable crypto self-tests

-- 
Jiri Bohac <jbohac@suse.cz>
SUSE Labs, Prague, Czechia


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  parent reply	other threads:[~2023-11-24 19:58 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-24 19:54 [PATCH 0/4] kdump: crashkernel reservation from CMA Jiri Bohac
2023-11-24 19:57 ` [PATCH 1/4] kdump: add crashkernel cma suffix Jiri Bohac
2023-11-25  7:24   ` kernel test robot
2023-11-24 19:58 ` [PATCH 2/4] kdump: implement reserve_crashkernel_cma Jiri Bohac
2023-11-24 19:58 ` [PATCH 3/4] kdump, x86: implement crashkernel CMA reservation Jiri Bohac
2023-11-24 19:58 ` Jiri Bohac [this message]
2023-11-25  1:51 ` [PATCH 0/4] kdump: crashkernel reservation from CMA Tao Liu
2023-11-25 21:22   ` Jiri Bohac
2023-11-28  1:12     ` Tao Liu
2023-11-28  2:11       ` Baoquan He
2023-11-28  9:08         ` Michal Hocko
2023-11-29  7:57           ` Baoquan He
2023-11-29  9:25             ` Michal Hocko
2023-11-30  2:42               ` Baoquan He
2023-11-29 10:51             ` Jiri Bohac
2023-11-30  4:01               ` Baoquan He
2023-12-01 12:35                 ` Jiri Bohac
2023-11-29  8:10           ` Baoquan He
2023-11-29 15:03             ` Donald Dutile
2023-11-30  3:00               ` Baoquan He
2023-11-30 10:16                 ` Michal Hocko
2023-11-30 12:04                   ` Baoquan He
2023-11-30 12:31                     ` Baoquan He
2023-11-30 13:41                       ` Michal Hocko
2023-12-01 11:33                         ` Philipp Rudo
2023-12-01 11:55                           ` Michal Hocko
2023-12-01 15:51                             ` Philipp Rudo
2023-12-01 16:59                               ` Michal Hocko
2023-12-06 11:08                                 ` Philipp Rudo
2023-12-06 11:23                                   ` David Hildenbrand
2023-12-06 13:49                                   ` Michal Hocko
2023-12-06 15:19                                     ` Michal Hocko
2023-12-07  4:23                                       ` Baoquan He
2023-12-07  8:55                                         ` Michal Hocko
2023-12-07 11:13                                           ` Philipp Rudo
2023-12-07 11:52                                             ` Michal Hocko
2023-12-08  1:55                                               ` Baoquan He
2023-12-08 10:04                                                 ` Michal Hocko
2023-12-08  2:10                                           ` Baoquan He
2023-12-07 11:13                                       ` Philipp Rudo
2023-11-30 13:29                     ` Michal Hocko
2023-11-30 13:33                       ` Pingfan Liu
2023-11-30 13:43                         ` Michal Hocko
2023-12-01  0:54                           ` Pingfan Liu
2023-12-01 10:37                             ` Michal Hocko
2023-11-28  2:07     ` Pingfan Liu
2023-11-28  8:58       ` Michal Hocko
2023-12-01 11:34 ` Philipp Rudo

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