* Re: [PATCH 0/4] powerpc/kdump: Support high crashkernel reservation
[not found] <20251027151338.819957-1-sourabhjain@linux.ibm.com>
@ 2025-10-28 6:23 ` Baoquan he
0 siblings, 0 replies; only message in thread
From: Baoquan he @ 2025-10-28 6:23 UTC (permalink / raw)
To: Sourabh Jain, kexec
Cc: linuxppc-dev, Hari Bathini, Madhavan Srinivasan,
Mahesh Salgaonkar, Michael Ellerman, Ritesh Harjani (IBM),
Shivang Upadhyay
Cc kexec mailing list.
On 10/27/25 at 08:43pm, Sourabh Jain wrote:
> Add support for reserving crashkernel memory in higher address ranges
> using the crashkernel=xxM,high command-line option.
>
> With this feature, most of the crashkernel memory for kdump will be
> reserved in high memory regions, while only a small portion (64 MB) will
> be reserved in low memory for the kdump kernel. This helps free up low
> memory for other components that require allocations in that region.
>
> For example, if crashkernel=2G,high is specified, the kernel will reserve
> 2 GB of crashkernel memory near the end of system RAM and an additional
> 64 MB of low memory (below 1 GB) for RTAS to function properly.
>
> Currently, this feature is supported only on PPC64 systems with 64-bit
> RTAS instantiation and Radix MMU enabled.
>
> Two critical changes were made to support this feature:
>
> - CPU feature discovery is now performed before crashkernel
> reservation. This ensures the MMU type is determined before reserving
> crashkernel memory. (Patch 01/04)
>
> - RTAS instantiation has been moved to 64-bit mode. (Patch 02/04)
>
> Apply the following patch first, and then apply this patch series:
> https://lore.kernel.org/all/20251024170118.297472-1-sourabhjain@linux.ibm.com/
>
> Cc: Baoquan he <bhe@redhat.com>
> Cc: Hari Bathini <hbathini@linux.ibm.com>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
>
> Sourabh Jain (4):
> powerpc/mmu: do MMU type discovery before crashkernel reservation
> powerpc: move to 64-bit RTAS
> powerpc/kdump: consider high crashkernel memory if enabled
> powerpc/kdump: add support for high crashkernel reservation
>
> arch/powerpc/include/asm/book3s/64/mmu.h | 1 +
> arch/powerpc/include/asm/crash_reserve.h | 8 +++++
> arch/powerpc/include/asm/kexec.h | 1 +
> arch/powerpc/include/asm/mmu.h | 1 +
> arch/powerpc/include/asm/rtas.h | 11 ++++++
> arch/powerpc/kernel/prom.c | 28 ++++++++-------
> arch/powerpc/kernel/prom_init.c | 26 +++++++++++---
> arch/powerpc/kernel/rtas.c | 5 +++
> arch/powerpc/kernel/rtas_entry.S | 17 ++++++++-
> arch/powerpc/kexec/core.c | 45 +++++++++++++++++-------
> arch/powerpc/kexec/elf_64.c | 10 ++++--
> arch/powerpc/kexec/file_load_64.c | 5 +--
> arch/powerpc/kexec/ranges.c | 24 +++++++++++--
> arch/powerpc/mm/init_64.c | 27 ++++++++------
> 14 files changed, 161 insertions(+), 48 deletions(-)
>
> --
> 2.51.0
>
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