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SubjectRe: [PATCH 0/5] arm64: add kdump support
Hi Akashi,

On Thursday 26 March 2015 01:58 PM, AKASHI Takahiro wrote:
> This patch set enables kdump (crash dump kernel) support on arm64 on top of
> Geoff's kexec patchset.
>
> In this version, there are some arm64-specific usage/constraints:
> 1) "mem=" boot parameter must be specified on crash dump kernel
> 2) Kvm will not be enabled on crash dump kernel even if configured
> See commit messages and Documentation/kdump/kdump.txt for details.
>
> The only concern I have is whether or not we can use the exact same kernel
> as both system kernel and crash dump kernel. The current arm64 kernel is
> not relocatable in the exact sense but I have no problems in using the same
> binary for testing kdump.
>
> I tested the code with
> - ATF v1.1 + EDK2(UEFI) v3.0-rc0
> - kernel v4.0-rc4 + Geoff' kexec v8
> on Base fast model, using my yet-to-be-submitted kexec-tools [1].
> You may want to start a kernel with the following boot parameter:
> crashkernel=64M@2240M
> and try
> $ kexec -p --load <vmlinux> --append ...
> $ echo c > /proc/sysrq-trigger
>

I tried to use your kdump patches for kernel and kexec-tools. I am not
able to load the crash kernel properly.


I passed crashkernel=64M@259G (My 8GB RAM starts at 256G) to primary kernel.

Used following to load the crash kernel
kexec -p --load vmlinux --append="$( cat /proc/cmdline ) maxcpus=1
mem=64M reset_devices"

I see:

kexec_load failed: Cannot assign requested address
entry = 0x40c40005d0 flags = 0xb70001

What I noticed that arm64_load_other_segments does not calculate correct
load address for purgatory or if I pass initrd then for that too within
crash kernel allocated memory.

Shouldn't we have a function similar to locate_dtb_in_crashmem for
putgatory as well as initrd? I can try to fix this allocation, but I was
just wondering if I understood correctly or I am missing something.

~Pratyush


> To examine vmcore (/proc/vmcore), you may use
> - gdb v7.7 or later
> - crash + a small patch (to recognize v4.0 kernel)
>
> [1] https://git.linaro.org/people/takahiro.akashi/kexec-tools.git
>
>
> AKASHI Takahiro (5):
> arm64: kdump: reserve memory for crash dump kernel
> arm64: kdump: implement machine_crash_shutdown()
> arm64: kdump: do not go into EL2 before starting a crash dump kernel
> arm64: add kdump support
> arm64: enable kdump in the arm64 defconfig
>
> Documentation/kdump/kdump.txt | 31 ++++++++++++++-
> arch/arm64/Kconfig | 12 ++++++
> arch/arm64/configs/defconfig | 1 +
> arch/arm64/include/asm/kexec.h | 34 +++++++++++++++-
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/crash_dump.c | 71 +++++++++++++++++++++++++++++++++
> arch/arm64/kernel/machine_kexec.c | 55 +++++++++++++++++++++++++-
> arch/arm64/kernel/process.c | 7 +++-
> arch/arm64/kernel/setup.c | 78 +++++++++++++++++++++++++++++++++++++
> arch/arm64/kernel/smp.c | 10 ++++-
> 10 files changed, 294 insertions(+), 6 deletions(-)
> create mode 100644 arch/arm64/kernel/crash_dump.c
>


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