On Tue, Jan 17, 2023 at 11:49:21AM +0800, Baoquan He wrote:
> This will help understand codes on crashkernel reservations on arm64.
FWIIW, I think you can fold this into the first patch.
And, although I have no good idea at this moment, I do wonder
if the logic can be simplified - I for one really needed the
comments to understand the retry logic.
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> ---
> arch/arm64/mm/init.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 26a05af2bfa8..f88ad17cb20d 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -177,6 +177,10 @@ static void __init reserve_crashkernel(void)
> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> search_base, crash_max);
> if (!crash_base) {
> + /*
> + * For crashkernel=size[KMG]@offset[KMG], print out failure
> + * message if can't reserve the specified region.
> + */
> if (fixed_base) {
> pr_warn("cannot reserve crashkernel region [0x%llx-0x%llx]\n",
> search_base, crash_max);
> @@ -188,6 +192,11 @@ static void __init reserve_crashkernel(void)
> * high memory, the minimum required low memory will be
> * reserved later.
> */
> + /*
> + * For crashkernel=size[KMG], if the first attempt was for
> + * low memory, fall back to high memory, the minimum required
> + * low memory will be reserved later.
> + */
I think this duplicates the preceding comment.
Perhaps just replace the earlier comment with this one.
> if (!high && crash_max == CRASH_ADDR_LOW_MAX) {
> crash_max = CRASH_ADDR_HIGH_MAX;
> search_base = CRASH_ADDR_LOW_MAX;
> @@ -195,6 +204,10 @@ static void __init reserve_crashkernel(void)
> goto retry;
> }
>
> + /*
> + * For crashkernel=size[KMG],high, if the first attempt was for
> + * high memory, fall back to low memory.
> + */
> if (high && (crash_max == CRASH_ADDR_HIGH_MAX)) {
> crash_max = CRASH_ADDR_LOW_MAX;
> search_base = 0;
> --
> 2.34.1
>
>
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