Re: [PATCH 00/18] Add FADump support on PowerNV platform

[Hari Bathini <hbathini@linux.ibm.com>]

On 27/02/19 9:07 AM, Daniel Axtens wrote:
> Hi Hari,


Hi Daniel,


>> Firmware-Assisted Dump (FADump) is currently supported only on pseries
>> platform. This patch series adds support for powernv platform too.
>>
>> The first and third patches refactor the FADump code to make use of common
>> code across multiple platforms. The fifth patch adds basic FADump support
>> for powernv platform. Patches seven & eight honour reserved-ranges DT node
>> while reserving/releasing memory used by FADump. The next patch processes
>> CPU state data provided by firmware to create and append core notes to the
>> ELF core file. The tenth patch adds support for preserving crash data for
>> subsequent boots (useful in cases like petitboot). Patch twelve provides
>> support to export opalcore. This is to make debugging of failures in OPAL
>> code easier. The subsequent patch ensures vmcore processing is skipped
>> when only OPAL core is exported by f/w. The next patch provides option to
>> release the kernel memory used to export opalcore. Patch seventeen adds
>> backup area (an area populated before crash and used in the capture kernel
>> to setup vmcore file robustly) support on PowerNV platform. The remaining
>> patches update Firmware-Assisted Dump documentation appropriately.
>>
>> Note that the quantam of increase in robustness due to patch seventeen may
>> not be worth breaking backward compatibility for older kernel versions.
>> Would like to hear thoughts from others on it.
>>
>> The patch series is tested with the latest firmware plus the below skiboot
>> changes for MPIPL support:
>>
>>      https://patchwork.ozlabs.org/project/skiboot/list/?series=78497
>>      ("MPIPL support")
>>
> If I want to test this, is there some userspace tooling that will
> extract a fadump from a rebooted system and allow me to examine it as I
> would with a kdump (e.g. with crash)?  I did look at
> Documentation/powerpc/firmware-assisted-dump.txt but it seems to only
> cover the kernel layer.

This patches export two dump files: /proc/vmcore (kernel), /proc/opalcore (OPAL).
If you are only interested in kernel dump, then passing fadump=on to the kernel
and enabling/starting kdump-tools/kdump service, shipped with distro, would ensure
dump is captured to /var/crash dir and rebooted but please be aware that the
script would not copy /proc/opalcore to disk yet. Need to update scripts once this
changes make it upstream..

Thanks
Hari