With CONFIG_SPARSEMEM disabled the below kernel build error is observed.
arch/powerpc/mm/init_64.c:477:38: error: use of undeclared identifier
'SECTION_SIZE_BITS'
CONFIG_MEMORY_HOTPLUG depends on CONFIG_SPARSEMEM and it is more clear
to describe the code dependency in terms of MEMORY_HOTPLUG. Outside
memory hotplug the kernel uses memory_block_size for kernel directmap.
Instead of depending on SECTION_SIZE_BITS to compute the direct map
page size, add a new #define which defaults to 16M(same as existing
SECTION_SIZE)
Fixes: 4d15721177d5 ("powerpc/mm: Cleanup memory block size probing")
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
---
arch/powerpc/mm/init_64.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index fcda46c2b8df..e3d7379ef480 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -472,12 +472,23 @@ static int __init dt_scan_mmu_pid_width(unsigned long
node,
return 1;
}
+/*
+ * Outside hotplug the kernel uses this value to map the kernel direct map
+ * with radix. To be compatible with older kernels, let's keep this value
+ * as 16M which is also SECTION_SIZE with SPARSEMEM. We can ideally map
+ * things with 1GB size in the case where we don't support hotplug.
+ */
+#ifndef CONFIG_MEMORY_HOTPLUG
+#define DEFAULT_MEMORY_BLOCK_SIZE SZ_16M
+#else
+#define DEFAULT_MEMORY_BLOCK_SIZE MIN_MEMORY_BLOCK_SIZE
+#endif
+
static void update_memory_block_size(unsigned long *block_size, unsigned long
mem_size)
{
- unsigned long section_size = 1UL << SECTION_SIZE_BITS;
-
- for (; *block_size > section_size; *block_size >>= 2) {
+ unsigned long min_memory_block_size = DEFAULT_MEMORY_BLOCK_SIZE;
+ for (; *block_size > min_memory_block_size; *block_size >>= 2) {
if ((mem_size & *block_size) == 0)
break;
}
@@ -507,7 +518,7 @@ static int __init probe_memory_block_size(unsigned long
node, const char *uname,
/*
* Nothing in the device tree
*/
- *block_size = MIN_MEMORY_BLOCK_SIZE;
+ *block_size = DEFAULT_MEMORY_BLOCK_SIZE;
else
*block_size = of_read_number(prop, dt_root_size_cells);
/*
--
2.41.0
