Re: [PATCH 0/2] kexec-tools: Fix split crash kernel reservations

[Simon Horman <horms@kernel.org>]

On Tue, Aug 18, 2026 at 08:35:05PM +0800, Rui Qi wrote:
> Hi,
> 
> This series fixes two kexec-tools issues seen with split crash kernel
> reservations.
> 
> The first patch makes --print-ckr-size prefer
> /sys/kernel/kexec_crash_size. This restores the option's original
> user-visible contract: report the same crash kernel reserved size and
> unit as the kernel sysfs attribute when that attribute is available.
> The existing arch load-range based calculation is kept as a fallback for
> older kernels.
> 
> The second patch fixes the RISC-V kexec_load crash path. RISC-V records
> all Crash kernel ranges from /proc/iomem, but it currently writes only
> the selected load range to linux,usable-memory-range. On systems with
> high/low crash kernel reservations, that prevents the crash kernel from
> seeing the low reservation after boot.
> 
> Keep placing the crash image segments in the selected load range, but
> pass all crash kernel ranges to the crash kernel through
> linux,usable-memory-range. This follows the split-reservation handoff
> model already used by arm64 kexec-tools, where
> linux,usable-memory-range = <BASE1 SIZE1 BASE2 SIZE2> advertises both
> high and low crash kernel ranges to the crash dump kernel.
> 
> Tested on riscv64 with:
> 
>   /proc/iomem:
>     f7e00000-ffdfffff       : Crash kernel  (128 MiB low)
>     1f88c00000-1ff6bfffff   : Crash kernel  (1760 MiB high)
> 
>   /sys/kernel/kexec_crash_size:
>     1979711488
> 
> With the patched kexec binary:
> 
>   kexec --print-ckr-size
>     1979711488
> 
>   kexec -c -p ... followed by a panic completed kdump successfully.
>   The crash kernel reported both ranges as System RAM in /proc/iomem:
> 
>     f7e00000-ffdfffff       : System RAM
>     1f88c00000-1ff6bfffff   : System RAM
> 
> The vmcore was saved successfully.
> 
> Rui Qi (2):
>   kexec: Print crash kernel reserved size from sysfs
>   RISC-V: Pass all crash kernel ranges to crash kernel

Thanks, applied.

- RISC-V: Pass all crash kernel ranges to crash kernel
  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=6b8b27fbe5cc
- kexec: Print crash kernel reserved size from sysfs
  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=97061549e25f


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