On 06/13/22 at 04:09pm, Zhen Lei wrote:
> For crashkernel=X without '@offset', select a region within DMA zones
> first, and fall back to reserve region above DMA zones. This allows
> users to use the same configuration on multiple platforms.
LGTM,
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 2 +-
> arch/arm64/mm/init.c | 16 +++++++++++++++-
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 61b179232b68001..fdac18beba5624e 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -823,7 +823,7 @@
> memory region [offset, offset + size] for that kernel
> image. If '@offset' is omitted, then a suitable offset
> is selected automatically.
> - [KNL, X86-64] Select a region under 4G first, and
> + [KNL, X86-64, ARM64] Select a region under 4G first, and
> fall back to reserve region above 4G when '@offset'
> hasn't been specified.
> See Documentation/admin-guide/kdump/kdump.rst for further details.
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 5390f361208ccf7..8539598f9e58b4d 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -138,6 +138,7 @@ static void __init reserve_crashkernel(void)
> unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
> char *cmdline = boot_command_line;
> int ret;
> + bool fixed_base;
>
> if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> return;
> @@ -166,15 +167,28 @@ static void __init reserve_crashkernel(void)
> return;
> }
>
> + fixed_base = !!crash_base;
> crash_size = PAGE_ALIGN(crash_size);
>
> /* User specifies base address explicitly. */
> - if (crash_base)
> + if (fixed_base)
> crash_max = crash_base + crash_size;
>
> +retry:
> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> crash_base, crash_max);
> if (!crash_base) {
> + /*
> + * Attempt to fully allocate low memory failed, fall back
> + * to high memory, the minimum required low memory will be
> + * reserved later.
> + */
> + if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) {
> + crash_max = CRASH_ADDR_HIGH_MAX;
> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> + goto retry;
> + }
> +
> pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> crash_size);
> return;
> --
> 2.25.1
>
