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From: Eric DeVolder <eric.devolder@oracle.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
	kexec@lists.infradead.org, ebiederm@xmission.com,
	dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, hpa@zytor.com,
	nramas@linux.microsoft.com, thomas.lendacky@amd.com,
	robh@kernel.org, efault@gmx.de, rppt@kernel.org,
	konrad.wilk@oracle.com, boris.ostrovsky@oracle.com,
	eric.devolder@oracle.com
Subject: [RFC v1 2/8] crash hp: Introduce CRASH_HOTPLUG configuration options
Date: Thu, 18 Nov 2021 12:49:42 -0500	[thread overview]
Message-ID: <20211118174948.37435-3-eric.devolder@oracle.com> (raw)
In-Reply-To: <20211118174948.37435-1-eric.devolder@oracle.com>

The bulk of the support for CPU and memory hotplug support for
crash is controlled by the CRASH_HOTPLUG configuration option,
introduced by this patch.

The CRASH_HOTPLUG_ELFCOREHDR_SZ related configuration option is
also introduced with this patch.

Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
---
 arch/x86/Kconfig | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 95dd1ee01546..5feb829adb60 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2046,6 +2046,32 @@ config CRASH_DUMP
 	  (CONFIG_RELOCATABLE=y).
 	  For more details see Documentation/admin-guide/kdump/kdump.rst
 
+config CRASH_HOTPLUG
+	bool "kernel updates of crash elfcorehdr"
+	depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) && KEXEC_FILE
+	help
+	  Enable the kernel to update the crash elfcorehdr (which contains
+	  the list of CPUs and memory regions) directly when hot plug/unplug
+	  of CPUs or memory. Otherwise userspace must monitor these hot
+	  plug/unplug change notifications via udev in order to
+	  unload-then-reload the crash kernel so that the list of CPUs and
+	  memory regions is kept up-to-date. Note that the udev CPU and
+	  memory change notifications still occur (however, userspace is not
+	  required to monitor for crash dump purposes).
+
+config CRASH_HOTPLUG_ELFCOREHDR_SZ
+	depends on CRASH_HOTPLUG
+	int
+	default 131072
+	help
+	  Specify the maximum size of the elfcorehdr buffer/segment.
+	  The 128KiB default is sized so that it can accommodate 2048
+	  Elf64_Phdr, where each Phdr represents either a CPU or a
+	  region of memory.
+	  For example, this size can accommodate hotplugging a machine
+	  with up to 1024 CPUs and up to 1024 memory regions (e.g. 1TiB
+	  with 1024 1GiB memory DIMMs).
+
 config KEXEC_JUMP
 	bool "kexec jump"
 	depends on KEXEC && HIBERNATION
-- 
2.27.0


WARNING: multiple messages have this Message-ID (diff)
From: Eric DeVolder <eric.devolder@oracle.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
	kexec@lists.infradead.org, ebiederm@xmission.com,
	dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, hpa@zytor.com,
	nramas@linux.microsoft.com, thomas.lendacky@amd.com,
	robh@kernel.org, efault@gmx.de, rppt@kernel.org,
	konrad.wilk@oracle.com, boris.ostrovsky@oracle.com,
	eric.devolder@oracle.com
Subject: [RFC v1 2/8] crash hp: Introduce CRASH_HOTPLUG configuration options
Date: Thu, 18 Nov 2021 12:49:42 -0500	[thread overview]
Message-ID: <20211118174948.37435-3-eric.devolder@oracle.com> (raw)
In-Reply-To: <20211118174948.37435-1-eric.devolder@oracle.com>

The bulk of the support for CPU and memory hotplug support for
crash is controlled by the CRASH_HOTPLUG configuration option,
introduced by this patch.

The CRASH_HOTPLUG_ELFCOREHDR_SZ related configuration option is
also introduced with this patch.

Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
---
 arch/x86/Kconfig | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 95dd1ee01546..5feb829adb60 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2046,6 +2046,32 @@ config CRASH_DUMP
 	  (CONFIG_RELOCATABLE=y).
 	  For more details see Documentation/admin-guide/kdump/kdump.rst
 
+config CRASH_HOTPLUG
+	bool "kernel updates of crash elfcorehdr"
+	depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) && KEXEC_FILE
+	help
+	  Enable the kernel to update the crash elfcorehdr (which contains
+	  the list of CPUs and memory regions) directly when hot plug/unplug
+	  of CPUs or memory. Otherwise userspace must monitor these hot
+	  plug/unplug change notifications via udev in order to
+	  unload-then-reload the crash kernel so that the list of CPUs and
+	  memory regions is kept up-to-date. Note that the udev CPU and
+	  memory change notifications still occur (however, userspace is not
+	  required to monitor for crash dump purposes).
+
+config CRASH_HOTPLUG_ELFCOREHDR_SZ
+	depends on CRASH_HOTPLUG
+	int
+	default 131072
+	help
+	  Specify the maximum size of the elfcorehdr buffer/segment.
+	  The 128KiB default is sized so that it can accommodate 2048
+	  Elf64_Phdr, where each Phdr represents either a CPU or a
+	  region of memory.
+	  For example, this size can accommodate hotplugging a machine
+	  with up to 1024 CPUs and up to 1024 memory regions (e.g. 1TiB
+	  with 1024 1GiB memory DIMMs).
+
 config KEXEC_JUMP
 	bool "kexec jump"
 	depends on KEXEC && HIBERNATION
-- 
2.27.0


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  parent reply	other threads:[~2021-11-18 17:51 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-18 17:49 [RFC v1 0/8] RFC v1: Kernel handling of CPU and memory hot un/plug for crash Eric DeVolder
2021-11-18 17:49 ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 1/8] crash: fix minor typo/bug in debug message Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-24  1:17   ` Baoquan He
2021-11-24  1:17     ` Baoquan He
2021-11-18 17:49 ` Eric DeVolder [this message]
2021-11-18 17:49   ` [RFC v1 2/8] crash hp: Introduce CRASH_HOTPLUG configuration options Eric DeVolder
2021-11-18 17:49 ` [RFC v1 3/8] crash hp: definitions and prototypes for crash hotplug support Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 4/8] crash hp: generic crash hotplug support infrastructure Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 5/8] crash hp: kexec_file changes for use by crash hotplug handler Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 6/8] crash hp: Add x86 crash hotplug state items to kimage Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 7/8] crash hp: Add x86 crash hotplug support for kexec_file_load Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-18 17:49 ` [RFC v1 8/8] crash hp: Add x86 crash hotplug support for bzImage Eric DeVolder
2021-11-18 17:49   ` Eric DeVolder
2021-11-19  2:37 ` [RFC v1 0/8] RFC v1: Kernel handling of CPU and memory hot un/plug for crash Baoquan He
2021-11-19  2:37   ` Baoquan He
2021-11-24  9:02 ` Baoquan He
2021-11-24  9:02   ` Baoquan He
2021-11-29 19:42   ` Eric DeVolder
2021-11-29 19:42     ` Eric DeVolder
2021-12-01 12:59     ` Baoquan He
2021-12-01 12:59       ` Baoquan He
2021-12-07 20:04       ` Eric DeVolder
2021-12-07 20:04         ` Eric DeVolder
2021-11-29  8:45 ` Sourabh Jain
2021-11-29  8:45   ` Sourabh Jain
2021-11-29 20:00   ` Eric DeVolder
2021-11-29 20:00     ` Eric DeVolder

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