Hi Sourabh,
Thanks for updating the documentation..
On 23/01/25 5:12 pm, Sourabh Jain wrote:
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.
Cc: Avnish Chouhan <avn...@linux.ibm.com>
Cc: Brian King <brk...@linux.ibm.com>
Cc: Hari Bathini <hbath...@linux.ibm.com>
Cc: Madhavan Srinivasan <ma...@linux.ibm.com>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Mahesh Salgaonkar <mah...@linux.ibm.com>
Signed-off-by: Sourabh Jain <sourabhj...@linux.ibm.com>
---
Documentation/ABI/testing/sysfs-kernel-fadump | 3 ++-
.../arch/powerpc/firmware-assisted-dump.rst | 22 +++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump
b/Documentation/ABI/testing/sysfs-kernel-fadump
index 2f9daa7ca55b..b64b7622e6fc 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump
@@ -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.
diff --git a/Documentation/arch/powerpc/firmware-assisted-dump.rst
b/Documentation/arch/powerpc/firmware-assisted-dump.rst
index 7e37aadd1f77..7e266e749cd5 100644
--- a/Documentation/arch/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/arch/powerpc/firmware-assisted-dump.rst
@@ -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
"Support to add additional kernel parameters to FADump capture kernel" ?
+ 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.
The below details are more appropriate in "Sysfs/debugfs files:" section
with the details going under /sys/kernel/fadump/bootargs_append:
+
+ Command to Add Additional Kernel Parameters to Fadump:
Do those words really need to start with Uppercase?
+ 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.
+
- Hari
