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Documentation/powerpc/fadump: add additional parameter feature details
Update the fadump document to include details about the fadump additional parameter feature. The document includes the following: - Significance of the feature - How to use it - Feature restrictions No functional changes are introduced. Signed-off-by: Sourabh Jain <[email protected]> Reviewed-by: Mahesh Salgaonkar <[email protected]> Signed-off-by: Madhavan Srinivasan <[email protected]> Link: https://patch.msgid.link/[email protected]
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Documentation/ABI/testing/sysfs-kernel-fadump

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Description: read/write
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This is a special sysfs file available to setup additional
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parameters to be passed to capture kernel.
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parameters to be passed to capture kernel. For HASH MMU it
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is exported only if RMA size higher than 768MB.

Documentation/arch/powerpc/firmware-assisted-dump.rst

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e.g.
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# echo 1 > /sys/firmware/opal/mpipl/release_core
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-- Support for Additional Kernel Arguments in Fadump
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Fadump has a feature that allows passing additional kernel arguments
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to the fadump kernel. This feature was primarily designed to disable
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kernel functionalities that are not required for the fadump kernel
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and to reduce its memory footprint while collecting the dump.
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Command to Add Additional Kernel Parameters to Fadump:
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e.g.
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# echo "nr_cpus=16" > /sys/kernel/fadump/bootargs_append
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The above command is sufficient to add additional arguments to fadump.
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An explicit service restart is not required.
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Command to Retrieve the Additional Fadump Arguments:
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e.g.
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# cat /sys/kernel/fadump/bootargs_append
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Note: Additional kernel arguments for fadump with HASH MMU is only
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supported if the RMA size is greater than 768 MB. If the RMA
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size is less than 768 MB, the kernel does not export the
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/sys/kernel/fadump/bootargs_append sysfs node.
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Implementation details:
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-----------------------
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