Update from V2: Adjust the doc.
Update from V1: Split into two patches and update docs as well.
Kairui Song (2): Disable device dump by default kexec-kdump-howto.txt: Add notes about device dump
kdump.sysconfig | 2 +- kdump.sysconfig.aarch64 | 2 +- kdump.sysconfig.i386 | 2 +- kdump.sysconfig.ppc64 | 2 +- kdump.sysconfig.ppc64le | 2 +- kdump.sysconfig.s390x | 2 +- kdump.sysconfig.x86_64 | 2 +- kexec-kdump-howto.txt | 17 +++++++++++++++++ 8 files changed, 24 insertions(+), 7 deletions(-)
Device dump may use a log of memory and cause OOM issue, so append "novmcoredd" option for second kernel and disable it by default. To use device dump, user should remove the vmcoredd parameter manually.
Signed-off-by: Kairui Song kasong@redhat.com --- kdump.sysconfig | 2 +- kdump.sysconfig.aarch64 | 2 +- kdump.sysconfig.i386 | 2 +- kdump.sysconfig.ppc64 | 2 +- kdump.sysconfig.ppc64le | 2 +- kdump.sysconfig.s390x | 2 +- kdump.sysconfig.x86_64 | 2 +- 7 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/kdump.sysconfig b/kdump.sysconfig index ffe1df8..df518d6 100644 --- a/kdump.sysconfig +++ b/kdump.sysconfig @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices" +KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty diff --git a/kdump.sysconfig.aarch64 b/kdump.sysconfig.aarch64 index c72a040..d5d7624 100644 --- a/kdump.sysconfig.aarch64 +++ b/kdump.sysconfig.aarch64 @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory udev.children-max=2 panic=10 swiotlb=noforce" +KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory udev.children-max=2 panic=10 swiotlb=noforce novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386 index b5ec653..c31a8cb 100644 --- a/kdump.sysconfig.i386 +++ b/kdump.sysconfig.i386 @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off udev.children-max=2 panic=10 transparent_hugepage=never" +KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64 index e142c6e..1f95452 100644 --- a/kdump.sysconfig.ppc64 +++ b/kdump.sysconfig.ppc64 @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never" +KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le index e142c6e..1f95452 100644 --- a/kdump.sysconfig.ppc64le +++ b/kdump.sysconfig.ppc64le @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never" +KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x index 6edc2fa..abd45a2 100644 --- a/kdump.sysconfig.s390x +++ b/kdump.sysconfig.s390x @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off udev.children-max=2 panic=10 transparent_hugepage=never" +KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off udev.children-max=2 panic=10 transparent_hugepage=never novmcoredd"
# Any additional /sbin/mkdumprd arguments required. MKDUMPRD_ARGS="" diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64 index 4a5ec1c..0ceed1f 100644 --- a/kdump.sysconfig.x86_64 +++ b/kdump.sysconfig.x86_64 @@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet"
# This variable lets us append arguments to the current kdump commandline # after processed by KDUMP_COMMANDLINE_REMOVE -KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 acpi_no_memhotplug transparent_hugepage=never nokaslr" +KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 acpi_no_memhotplug transparent_hugepage=never nokaslr novmcoredd"
# Any additional kexec arguments required. In most situations, this should # be left empty
Currently there are two issues with device dump: - It may use too much memory - kdump won't automatically include required driver in second kernel
User should manually reserve enough memory, and include the required driver by using extra_modules. Add some notes about the issues in kexec-kdump-howto.txt
Signed-off-by: Kairui Song kasong@redhat.com --- kexec-kdump-howto.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt index 7e9e58a..8e6cc4c 100644 --- a/kexec-kdump-howto.txt +++ b/kexec-kdump-howto.txt @@ -698,6 +698,23 @@ crash kernel according, or update your encryption setup. It's recommanded to use a non-encrypted target (eg. remote target) instead.
+Notes on device dump: + +Device dump allows drivers to append dump data to vmcore, so you can +collect driver specified debug info. The drivers could append the +data without any limit, and the data is stored in memory, this may +bring a significant memory stress. So device dump is disabled by default +by passing "novmcoredd" command line option to the kdump capture kernel. +If you want to collect debug data with device dump, you need to modify +"KDUMP_COMMANDLINE_APPEND=" value in /etc/sysconfig/kdump and remove the +"novmcoredd" option. You also need to increase the "crashkernel=" value +accordingly in case of OOM issue. +Besides, kdump initramfs won't automatically include the device drivers +which support device dump, only device drivers that are required for +the dump target setup will be included. To ensure the device dump data +will be included in the vmcore, you need to force include related +device drivers by using "extra_modules" option in /etc/kdump.conf + Parallel Dumping Operation ========================== Kexec allows kdump using multiple cpus. So parallel feature can accelerate
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Kairui Song