[PATCH v24 0/9] arm64: add kdump support

[mjaggi@caviumnetworks.com (Manish Jaggi)]

On 08/31/2016 11:01 AM, AKASHI Takahiro wrote:
> Manish,
> 
> Thank you for testing my kdump and reporting issues.
> 
> On Wed, Aug 31, 2016 at 09:11:52AM +0530, Manish Jaggi wrote:
>> Hi Akashi,
>>
>> On 08/09/2016 07:22 AM, AKASHI Takahiro wrote:
>>> This patch series adds kdump support on arm64.
>>>
>>> To load a crash-dump kernel to the systems, a series of patches to
>>> kexec-tools, which have not yet been merged upstream, are needed.
>>> Please use my kdump patches [1].
>>>
>>> To examine vmcore (/proc/vmcore) on a crash-dump kernel, you can use
>>>   - crash utility (coming v7.1.6 or later) [2]
>>>     (Necessary patches have already been queued in the master.)
>>>
>>> [1] T.B.D.
>>> [2] https://github.com/crash-utility/crash.git
>>>
>>> Changes for v24 (Aug 9, 2016):
>>>   o Rebase to Linux-4.8-rc1
>>>   o Update descriptions about newly added DT proerties
>>>
>>> Changes for v23 (July 26, 2016):
>>>
>>>   o Move memblock_reserve() to a single place in reserve_crashkernel()
>>>   o Use  cpu_park_loop() in ipi_cpu_crash_stop()
>>>   o Always enforce ARCH_LOW_ADDRESS_LIMIT to the memory range of crash kernel
>>>   o Re-implement fdt_enforce_memory_region() to remove non-reserve regions
>>>     (for ACPI) from usable memory at crash kernel
>>>
>>> Changes for v22 (July 12, 2016):
>>>
>>>   o Export "crashkernel-base" and "crashkernel-size" via device-tree,
>>>     and add some descriptions about them in chosen.txt
>>>   o Rename "usable-memory" to "usable-memory-range" to avoid inconsistency
>>>     with powerpc's "usable-memory"
>>>   o Make cosmetic changes regarding "ifdef" usage
>>>   o Correct some wordings in kdump.txt
>>>
>>> Changes for v21 (July 6, 2016):
>>>
>>>   o Remove kexec patches.
>>>   o Rebase to arm64's for-next/core (Linux-4.7-rc4 based).
>>>   o Clarify the description about kvm in kdump.txt.
>>>
>>> See the following link [3] for older changes:
>>> [3]  http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438780.html
>>>
>>> AKASHI Takahiro (8):
>>>   arm64: kdump: reserve memory for crash dump kernel
>>>   memblock: add memblock_cap_memory_range()
>>>   arm64: limit memory regions based on DT property, usable-memory-range
>>>   arm64: kdump: implement machine_crash_shutdown()
>>>   arm64: kdump: add kdump support
>>>   arm64: kdump: add VMCOREINFO's for user-space coredump tools
>>>   arm64: kdump: enable kdump in the arm64 defconfig
>>>   arm64: kdump: update a kernel doc
>>>
>>> James Morse (1):
>>>   Documentation: dt: chosen properties for arm64 kdump
>>>
>>>  Documentation/devicetree/bindings/chosen.txt |  45 ++++++
>>>  Documentation/kdump/kdump.txt                |  16 ++-
>>>  arch/arm64/Kconfig                           |  11 ++
>>>  arch/arm64/configs/defconfig                 |   1 +
>>>  arch/arm64/include/asm/hardirq.h             |   2 +-
>>>  arch/arm64/include/asm/kexec.h               |  41 +++++-
>>>  arch/arm64/include/asm/smp.h                 |   2 +
>>>  arch/arm64/kernel/Makefile                   |   1 +
>>>  arch/arm64/kernel/crash_dump.c               |  71 ++++++++++
>>>  arch/arm64/kernel/machine_kexec.c            |  67 ++++++++-
>>>  arch/arm64/kernel/setup.c                    |   7 +-
>>>  arch/arm64/kernel/smp.c                      |  63 +++++++++
>>>  arch/arm64/mm/init.c                         | 202 +++++++++++++++++++++++++++
>>>  include/linux/memblock.h                     |   1 +
>>>  mm/memblock.c                                |  28 ++++
>>>  15 files changed, 551 insertions(+), 7 deletions(-)
>>>  create mode 100644 arch/arm64/kernel/crash_dump.c
>>>
>> Couple of points
>> a) Just a note, while testing, the crashkernel reserved memory should be less than ARCH_LOW_ADDRESS_LIMIT (=arm64_dma_phys_limit).
> 
> I think that this is a common mistake not only for kdump, but also
> for general kernels.
> Since request_standard_resources() calls alloc_bootmem_low(),
> the kernel will panic if any of usable "System RAM" is located
> above ARCH_LOW_ADDRESS_LIMIT.
> For kdump, using "crashkernel=SS" notation is a convenient way
> to avoid this issue.
> 
>> b) Has anyone tested this on a SoC with Gicv3 ITS ?
>> Should the GICD/R be reset prior to switching to crash kernel ?
>> I am seeing lot of GICv3: RWP timeout, gone fishing while crash kernel boots.
> 
> I've never seen this kind of messages.
> I usually do my testing on a fast model.
> "compatible" of interrupt-controller is "arm,gic-v3."
> 
I suspect gic_cpu_pm_notifier is not being called on any of the cores prior to start of crash kernel.
We might have to call it explicitly.
> Thanks,
> -Takahiro AKASHI
> 
>> Thanks,
>> Manish