[PATCH v3 1/4] powerpc: export MIN RMA size

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Commit 683eab94da75bc ("powerpc/fadump: setup additional parameters for
dump capture kernel") introduced the additional parameter feature in
fadump for HASH MMU with the understanding that GRUB does not use the
memory area between 640MB and 768MB for its operation.

However, the third patch ("powerpc: increase MIN RMA size for CAS
negotiation") in this series is changing the MIN RMA size to 768MB,
allowing GRUB to use memory up to 768MB. This makes the fadump
reservation for the additional parameter feature for HASH MMU
unreliable.

To address this, export the MIN_RMA so that the next patch
("powerpc/fadump: fix additional param memory reservation for HASH MMU")
can identify the correct memory range for the additional parameter
feature in fadump for HASH MMU.

Cc: Avnish Chouhan <avnish@linux.ibm.com>
Cc: Brian King <brking@linux.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/include/asm/prom.h | 2 ++
 arch/powerpc/kernel/prom_init.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
index c0107d8ddd8c..b4e504b914e4 100644
--- a/arch/powerpc/include/asm/prom.h
+++ b/arch/powerpc/include/asm/prom.h
@@ -17,6 +17,8 @@
 struct device_node;
 struct property;
 
+#define MIN_RMA			512		/* Minimum RMA (in MB) for CAS negotiation */
+
 #define OF_DT_BEGIN_NODE	0x1		/* Start of node, full name */
 #define OF_DT_END_NODE		0x2		/* End node */
 #define OF_DT_PROP		0x3		/* Property: name off, size,
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 8e776ba39497..7daecf1b7c16 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -1061,7 +1061,7 @@ static const struct ibm_arch_vec ibm_architecture_vec_template __initconst = {
 		.virt_base = cpu_to_be32(0xffffffff),
 		.virt_size = cpu_to_be32(0xffffffff),
 		.load_base = cpu_to_be32(0xffffffff),
-		.min_rma = cpu_to_be32(512),		/* 512MB min RMA */
+		.min_rma = cpu_to_be32(MIN_RMA),
 		.min_load = cpu_to_be32(0xffffffff),	/* full client load */
 		.min_rma_percent = 0,	/* min RMA percentage of total RAM */
 		.max_pft_size = 48,	/* max log_2(hash table size) */
-- 
2.48.1