Re: [PATCH v14 07/11] arm64: kdump: introduce some macroes for crash kernel reservation

On Thu, 2021-02-04 at 17:20 +0100, Nicolas Saenz Julienne wrote:

Hi Chen,

On Sat, 2021-01-30 at 15:10 +0800, Chen Zhou wrote:

quoted

Introduce macro CRASH_ALIGN for alignment, macro CRASH_ADDR_LOW_MAX
for upper bound of low crash memory, macro CRASH_ADDR_HIGH_MAX for
upper bound of high crash memory, use macroes instead.

Besides, keep consistent with x86, use CRASH_ALIGN as the lower bound
of crash kernel reservation.

Signed-off-by: Chen Zhou <redacted>
Tested-by: John Donnelly <redacted>
---
 arch/arm64/include/asm/kexec.h | 6 ++++++
 arch/arm64/mm/init.c           | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index d24b527e8c00..3f6ecae0bc68 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h

@@ -25,6 +25,12 @@

 

 #define KEXEC_ARCH KEXEC_ARCH_AARCH64
 

+/* 2M alignment for crash kernel regions */
+#define CRASH_ALIGN	SZ_2M
+
+#define CRASH_ADDR_LOW_MAX	arm64_dma_phys_limit

I wonder if you could use 'ARCH_LOW_ADDRESS_LIMIT', instead of creating a new
define.

quoted

+#define CRASH_ADDR_HIGH_MAX	MEMBLOCK_ALLOC_ACCESSIBLE
+
 #ifndef __ASSEMBLY__
 

 /**

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 709d98fea90c..912f64f505f7 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -84,8 +84,8 @@ static void __init reserve_crashkernel(void)

 

 	if (crash_base == 0) {
 		/* Current arm64 boot protocol requires 2MB alignment */
-		crash_base = memblock_find_in_range(0, arm64_dma_phys_limit,
-				crash_size, SZ_2M);
+		crash_base = memblock_find_in_range(CRASH_ALIGN, CRASH_ADDR_LOW_MAX,
+				crash_size, CRASH_ALIGN);

Actually we could get rid of CRASH_ADDR_LOW_MAX altogether if we used
memblock_alloc_low() here (modulo the slight refactoring needed to accommodate
it).

Forget about these coments, I now see that you're deleting this whole function
on the next patch and defaulting to a generic implementation. Sorry for the
noise.

Regards,
Nicolas