[PATCH v13 3/8] x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions reserve_crashkernel()

[Chen Zhou]

To make the functions reserve_crashkernel() as generic,
replace some hard-coded numbers with macro CRASH_ADDR_LOW_MAX.

Signed-off-by: Chen Zhou <chenzho...@huawei.com>
Tested-by: John Donnelly <john.p.donne...@oracle.com>
---
 arch/x86/kernel/setup.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d1599449a001..1289f079ad5f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -491,8 +491,9 @@ static void __init reserve_crashkernel(void)
        if (!crash_base) {
                /*
                 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
-                * crashkernel=x,high reserves memory over 4G, also allocates
-                * 256M extra low memory for DMA buffers and swiotlb.
+                * crashkernel=x,high reserves memory over CRASH_ADDR_LOW_MAX,
+                * also allocates 256M extra low memory for DMA buffers
+                * and swiotlb.
                 * But the extra memory is not required for all machines.
                 * So try low memory first and fall back to high memory
                 * unless "crashkernel=size[KMG],high" is specified.
@@ -520,7 +521,7 @@ static void __init reserve_crashkernel(void)
                }
        }
 
-       if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
+       if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
                memblock_free(crash_base, crash_size);
                return;
        }
-- 
2.20.1