Documentation/kdump/kdump.txt: add ARM description
Add arm specific parts to kdump kernel documentation. Signed-off-by: Hu Keping <hukeping@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: Haren Myneni <hbabu@us.ibm.com> Cc: Rob Landley <rob@landley.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -18,7 +18,7 @@ memory image to a dump file on the local disk, or across the network to
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a remote system.
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a remote system.
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Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
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Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64,
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and s390x architectures.
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s390x and arm architectures.
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When the system kernel boots, it reserves a small section of memory for
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When the system kernel boots, it reserves a small section of memory for
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the dump-capture kernel. This ensures that ongoing Direct Memory Access
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the dump-capture kernel. This ensures that ongoing Direct Memory Access
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@ -112,7 +112,7 @@ There are two possible methods of using Kdump.
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2) Or use the system kernel binary itself as dump-capture kernel and there is
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2) Or use the system kernel binary itself as dump-capture kernel and there is
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no need to build a separate dump-capture kernel. This is possible
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no need to build a separate dump-capture kernel. This is possible
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only with the architectures which support a relocatable kernel. As
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only with the architectures which support a relocatable kernel. As
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of today, i386, x86_64, ppc64 and ia64 architectures support relocatable
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of today, i386, x86_64, ppc64, ia64 and arm architectures support relocatable
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kernel.
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kernel.
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Building a relocatable kernel is advantageous from the point of view that
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Building a relocatable kernel is advantageous from the point of view that
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@ -241,6 +241,13 @@ Dump-capture kernel config options (Arch Dependent, ia64)
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kernel will be aligned to 64Mb, so if the start address is not then
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kernel will be aligned to 64Mb, so if the start address is not then
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any space below the alignment point will be wasted.
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any space below the alignment point will be wasted.
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Dump-capture kernel config options (Arch Dependent, arm)
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----------------------------------------------------------
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- To use a relocatable kernel,
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Enable "AUTO_ZRELADDR" support under "Boot" options:
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AUTO_ZRELADDR=y
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Extended crashkernel syntax
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Extended crashkernel syntax
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===========================
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===========================
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@ -256,6 +263,10 @@ The syntax is:
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crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
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crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
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range=start-[end]
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range=start-[end]
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Please note, on arm, the offset is required.
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crashkernel=<range1>:<size1>[,<range2>:<size2>,...]@offset
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range=start-[end]
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'start' is inclusive and 'end' is exclusive.
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'start' is inclusive and 'end' is exclusive.
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For example:
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For example:
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@ -296,6 +307,12 @@ Boot into System Kernel
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on the memory consumption of the kdump system. In general this is not
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on the memory consumption of the kdump system. In general this is not
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dependent on the memory size of the production system.
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dependent on the memory size of the production system.
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On arm, use "crashkernel=Y@X". Note that the start address of the kernel
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will be aligned to 128MiB (0x08000000), so if the start address is not then
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any space below the alignment point may be overwritten by the dump-capture kernel,
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which means it is possible that the vmcore is not that precise as expected.
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Load the Dump-capture Kernel
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Load the Dump-capture Kernel
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============================
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============================
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@ -315,7 +332,8 @@ For ia64:
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- Use vmlinux or vmlinuz.gz
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- Use vmlinux or vmlinuz.gz
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For s390x:
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For s390x:
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- Use image or bzImage
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- Use image or bzImage
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For arm:
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- Use zImage
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If you are using a uncompressed vmlinux image then use following command
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If you are using a uncompressed vmlinux image then use following command
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to load dump-capture kernel.
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to load dump-capture kernel.
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@ -331,6 +349,15 @@ to load dump-capture kernel.
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--initrd=<initrd-for-dump-capture-kernel> \
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--initrd=<initrd-for-dump-capture-kernel> \
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--append="root=<root-dev> <arch-specific-options>"
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--append="root=<root-dev> <arch-specific-options>"
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If you are using a compressed zImage, then use following command
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to load dump-capture kernel.
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kexec --type zImage -p <dump-capture-kernel-bzImage> \
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--initrd=<initrd-for-dump-capture-kernel> \
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--dtb=<dtb-for-dump-capture-kernel> \
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--append="root=<root-dev> <arch-specific-options>"
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Please note, that --args-linux does not need to be specified for ia64.
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Please note, that --args-linux does not need to be specified for ia64.
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It is planned to make this a no-op on that architecture, but for now
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It is planned to make this a no-op on that architecture, but for now
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it should be omitted
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it should be omitted
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@ -347,6 +374,9 @@ For ppc64:
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For s390x:
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For s390x:
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"1 maxcpus=1 cgroup_disable=memory"
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"1 maxcpus=1 cgroup_disable=memory"
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For arm:
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"1 maxcpus=1 reset_devices"
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Notes on loading the dump-capture kernel:
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Notes on loading the dump-capture kernel:
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* By default, the ELF headers are stored in ELF64 format to support
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* By default, the ELF headers are stored in ELF64 format to support
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