[dm-devel] [PATCH v6 1/2] dax: introduce CONFIG_DAX_DRIVER

[Dan Williams]

In support of allowing device-mapper to compile out idle/dead code when
there are no dax providers in the system, introduce the DAX_DRIVER
symbol. This is selected by all leaf drivers that device-mapper might be
layered on top. This allows device-mapper to conditionally 'select DAX'
only when a provider is present.

Cc: Paul Mackerras <paulus at samba.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky at de.ibm.com>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer at de.ibm.com>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Mike Snitzer <snitzer at redhat.com>
Cc: Bart Van Assche <Bart.VanAssche at wdc.com>
Signed-off-by: Dan Williams <dan.j.williams at intel.com>
---
 arch/powerpc/platforms/Kconfig |    2 +-
 drivers/dax/Kconfig            |    5 ++++-
 drivers/nvdimm/Kconfig         |    2 +-
 drivers/s390/block/Kconfig     |    2 +-
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 5a96a2763e4a..1c14b943d9ff 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -296,7 +296,7 @@ config CPM2
 config AXON_RAM
 	tristate "Axon DDR2 memory device driver"
 	depends on PPC_IBM_CELL_BLADE && BLOCK
-	select DAX
+	select DAX_DRIVER
 	default m
 	help
 	  It registers one block device per Axon's DDR2 memory bank found
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index b79aa8f7a497..e0700bf4893a 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -1,3 +1,7 @@
+config DAX_DRIVER
+	select DAX
+	bool
+
 menuconfig DAX
 	tristate "DAX: direct access to differentiated memory"
 	select SRCU
@@ -16,7 +20,6 @@ config DEV_DAX
 	  baseline memory pool.  Mappings of a /dev/daxX.Y device impose
 	  restrictions that make the mapping behavior deterministic.
 
-
 config DEV_DAX_PMEM
 	tristate "PMEM DAX: direct access to persistent memory"
 	depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index a65f2e1d9f53..40cbdb16e23e 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -20,7 +20,7 @@ if LIBNVDIMM
 config BLK_DEV_PMEM
 	tristate "PMEM: Persistent memory block device support"
 	default LIBNVDIMM
-	select DAX
+	select DAX_DRIVER
 	select ND_BTT if BTT
 	select ND_PFN if NVDIMM_PFN
 	help
diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig
index 31f014b57bfc..5c4d6f8ff0e5 100644
--- a/drivers/s390/block/Kconfig
+++ b/drivers/s390/block/Kconfig
@@ -14,7 +14,7 @@ config BLK_DEV_XPRAM
 
 config DCSSBLK
 	def_tristate m
-	select DAX
+	select DAX_DRIVER
 	prompt "DCSSBLK support"
 	depends on S390 && BLOCK
 	help