Commit 61c403b5 authored by Sourabh Jain's avatar Sourabh Jain Committed by Madhavan Srinivasan
Browse files

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: default avatarSourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: default avatarMahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250123114254.200527-5-sourabhjain@linux.ibm.com
parent fdc44538

Documentation/ABI/testing/sysfs-kernel-fadump

+2 −1
Original line number Diff line number Diff line
@@ -55,4 +55,5 @@ Date: May 2024 
Contact:	linuxppc-dev@lists.ozlabs.org

Description:	read/write

		This is a special sysfs file available to setup additional

		parameters to be passed to capture kernel.
 
		parameters to be passed to capture kernel. For HASH MMU it

		is exported only if RMA size higher than 768MB.

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

+22 −0
Original line number Diff line number Diff line
@@ -120,6 +120,28 @@ to ensure that crash data is preserved to process later. 
   e.g.

     # echo 1 > /sys/firmware/opal/mpipl/release_core



-- Support for Additional Kernel Arguments in Fadump

   Fadump has a feature that allows passing additional kernel arguments

   to the fadump kernel. This feature was primarily designed to disable

   kernel functionalities that are not required for the fadump kernel

   and to reduce its memory footprint while collecting the dump.



  Command to Add Additional Kernel Parameters to Fadump:

  e.g.

  # echo "nr_cpus=16" > /sys/kernel/fadump/bootargs_append



  The above command is sufficient to add additional arguments to fadump.

  An explicit service restart is not required.



  Command to Retrieve the Additional Fadump Arguments:

  e.g.

  # cat /sys/kernel/fadump/bootargs_append



Note: Additional kernel arguments for fadump with HASH MMU is only

      supported if the RMA size is greater than 768 MB. If the RMA

      size is less than 768 MB, the kernel does not export the

      /sys/kernel/fadump/bootargs_append sysfs node.



Implementation details:

-----------------------