powerpc/fadump: update documentation about option to release opalcore

With /sys/firmware/opal/core support available on OPAL based machines
and an option to the release memory used by kernel in exporting this
core file, update FADump documentation with these details.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821382786.5656.13173494907671241231.stgit@hbathini.in.ibm.com
This commit is contained in:
Hari Bathini 2019-09-11 20:27:12 +05:30 committed by Michael Ellerman
parent 7b1b3b4825
commit b3bba79d5a
1 changed files with 19 additions and 0 deletions

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@ -110,6 +110,16 @@ capture kernel boot to process this crash data. Kernel config
option CONFIG_PRESERVE_FA_DUMP has to be enabled on such kernel
to ensure that crash data is preserved to process later.
-- On OPAL based machines (PowerNV), if the kernel is build with
CONFIG_OPAL_CORE=y, OPAL memory at the time of crash is also
exported as /sys/firmware/opal/core file. This procfs file is
helpful in debugging OPAL crashes with GDB. The kernel memory
used for exporting this procfs file can be released by echo'ing
'1' to /sys/kernel/fadump_release_opalcore node.
e.g.
# echo 1 > /sys/kernel/fadump_release_opalcore
Implementation details:
-----------------------
@ -273,6 +283,15 @@ Here is the list of files under kernel sysfs:
enhanced to use this interface to release the memory reserved for
dump and continue without 2nd reboot.
/sys/kernel/fadump_release_opalcore
This file is available only on OPAL based machines when FADump is
active during capture kernel. This is used to release the memory
used by the kernel to export /sys/firmware/opal/core file. To
release this memory, echo '1' to it:
echo 1 > /sys/kernel/fadump_release_opalcore
Here is the list of files under powerpc debugfs:
(Assuming debugfs is mounted on /sys/kernel/debug directory.)