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From: Masayoshi Mizuma <msys.mizuma@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Baoquan He <bhe@redhat.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>,
	Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 3/3] docs: kernel-parameters.txt: document rand_mem_physical_padding
Date: Mon,  1 Oct 2018 10:08:43 -0400	[thread overview]
Message-ID: <20181001140843.26137-4-msys.mizuma@gmail.com> (raw)
In-Reply-To: <20181001140843.26137-1-msys.mizuma@gmail.com>

From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

This kernel parameter allows to change the padding used
for the physical memory mapping section when KASLR
memory is enabled.

For memory hotplug capable systems, the default padding size,
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING, may not be enough.
The option is useful to adjust the padding size.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
---
 .../admin-guide/kernel-parameters.txt          | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 92eb1f4..4c4c5e6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3529,6 +3529,24 @@
 			fully seed the kernel's CRNG. Default is controlled
 			by CONFIG_RANDOM_TRUST_CPU.
 
+	rand_mem_physical_padding=
+			[KNL] Define the padding size in terabytes
+			used for the physical memory mapping section
+			when KASLR is enabled.
+			If the padding size is not enough, you can see
+			'Set rand_mem_physical_padding=XX ...' in system
+			boot message, so set the parameter as the message.
+
+			This parameter is useful for the memory hot-add capable
+			system. Such system may have more space than
+			actual memory size to hot-add memory. If the
+			padding size is not enough and a memory is hot-added,
+			the hot-adding will fail because it destroys the
+			system memory map. So, the padding size is needed to
+			adjust in such system.
+			The default value is
+			CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING.
+
 	ras=option[,option,...]	[KNL] RAS-specific options
 
 		cec_disable	[X86]
-- 
2.18.0


  parent reply	other threads:[~2018-10-01 14:09 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01 14:08 [PATCH v5 0/3] Add a kernel parameter to change the padding size for KASLR Masayoshi Mizuma
2018-10-01 14:08 ` [PATCH v5 1/3] x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping Masayoshi Mizuma
2018-10-02 10:18   ` [tip:x86/boot] " tip-bot for Masayoshi Mizuma
2018-10-01 14:08 ` [PATCH v5 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough Masayoshi Mizuma
2018-10-02 10:18   ` [tip:x86/boot] ACPI/NUMA: " tip-bot for Masayoshi Mizuma
2018-10-02 15:05     ` Borislav Petkov
2018-10-02 21:19       ` Masayoshi Mizuma
2018-10-03 10:58     ` Masayoshi Mizuma
2018-10-03 12:34     ` Peter Zijlstra
2018-10-03 12:48       ` Borislav Petkov
2018-10-03 13:02         ` Masayoshi Mizuma
2018-10-03 14:21       ` [tip:x86/boot] x86/kaslr, ACPI/NUMA: Fix KASLR build error tip-bot for Peter Zijlstra (Intel)
2018-10-08 11:03         ` Naresh Kamboju
2018-10-08 13:01           ` Borislav Petkov
2018-10-08 13:48             ` Arnd Bergmann
2018-10-08 14:10               ` Borislav Petkov
2018-10-09 10:39       ` tip-bot for Peter Zijlstra (Intel)
2018-10-01 14:08 ` Masayoshi Mizuma [this message]
2018-10-02 10:19   ` [tip:x86/boot] Documentation/kernel-parameters.txt: Document rand_mem_physical_padding= tip-bot for Masayoshi Mizuma

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