Re: [PATCH v20 2/5] arm64: kdump: introduce some macros for crash kernel reservation

On 2022/2/11 18:39, Baoquan He wrote:

On 01/24/22 at 04:47pm, Zhen Lei wrote:

quoted

From: Chen Zhou <redacted>

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 macros instead.

Signed-off-by: Chen Zhou <redacted>
Signed-off-by: Zhen Lei <redacted>
Tested-by: John Donnelly <redacted>
Tested-by: Dave Kleikamp <redacted>
---
 arch/arm64/mm/init.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 90f276d46b93bc6..6c653a2c7cff052 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -65,6 +65,12 @@ EXPORT_SYMBOL(memstart_addr);
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
 #ifdef CONFIG_KEXEC_CORE
+/* Current arm64 boot protocol requires 2MB alignment */
+#define CRASH_ALIGN		SZ_2M
+
+#define CRASH_ADDR_LOW_MAX	arm64_dma_phys_limit
+#define CRASH_ADDR_HIGH_MAX	MEMBLOCK_ALLOC_ACCESSIBLE

MEMBLOCK_ALLOC_ACCESSIBLE is obvoiously a alloc flag for memblock
allocator, I don't think it's appropriate to make HIGH_MAX get its value.

Right, thanks.

You can make it as memblock.current_limit, or do not define it, but using
MEMBLOCK_ALLOC_ACCESSIBLE direclty in memblock_phys_alloc_range() with
a code comment. 

This patch is not required at present. These macros are added to eliminate
differences to share code with x86.

quoted

+
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *

@@ -75,7 +81,7 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size;
-	unsigned long long crash_max = arm64_dma_phys_limit;
+	unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
 	int ret;
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),

@@ -90,8 +96,7 @@ static void __init reserve_crashkernel(void)
 	if (crash_base)
 		crash_max = crash_base + crash_size;
 
-	/* Current arm64 boot protocol requires 2MB alignment */
-	crash_base = memblock_phys_alloc_range(crash_size, SZ_2M,
+	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
 					       crash_base, crash_max);
 	if (!crash_base) {
 		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",

-- 
2.25.1

.

-- 
Regards,
  Zhen Lei

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