This will help understand codes on crashkernel reservations on arm64.
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.
+ */
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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