CONFIG_CXL_DEBUG=y adds -DDEBUG to CFLAGS, which enables pr_debug()
and dev_dbg(). Users can use this config to open all cxl debug
messages.

Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
---
 drivers/cxl/Kconfig  | 10 ++++++++++
 drivers/cxl/Makefile |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index 48b7314afdb8..b7e5225e9d7c 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -233,4 +233,14 @@ config CXL_MCE
 	def_bool y
 	depends on X86_MCE && MEMORY_FAILURE
 
+config CXL_DEBUG
+	bool "CXL Debugging"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here if you want the CXL core to produce a bunch of debug
+	  messages to the system log.  Select this if you are having a
+	  problem with CXL support and want to see more of what is going on.
+
+	  When in doubt, say N.
+
 endif
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index 2caa90fa4bf2..9c0151a2b201 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -19,3 +19,5 @@ cxl_acpi-y := acpi.o
 cxl_pmem-y := pmem.o security.o
 cxl_mem-y := mem.o
 cxl_pci-y := pci.o
+
+subdir-ccflags-$(CONFIG_CXL_DEBUG) := -DDEBUG
-- 
2.34.1

Yuquan Wang wrote:
> CONFIG_CXL_DEBUG=y adds -DDEBUG to CFLAGS, which enables pr_debug()
> and dev_dbg(). Users can use this config to open all cxl debug
> messages.

There is no need for this.

Dynamic debugging can be turned on at run time.[1]

For example here is what run_qemu[2] adds to the cmdline to debug cxl with
cxl-test.

cxl_acpi.dyndbg=+fplm cxl_pci.dyndbg=+fplm cxl_core.dyndbg=+fplm
cxl_mem.dyndbg=+fplm cxl_pmem.dyndbg=+fplm cxl_port.dyndbg=+fplm
cxl_region.dyndbg=+fplm cxl_test.dyndbg=+fplm cxl_mock.dyndbg=+fplm
cxl_mock_mem.dyndbg=+fplm

Ira

[1] https://www.kernel.org/doc/html/v4.14/admin-guide/dynamic-debug-howto.html
[2] https://github.com/pmem/run_qemu

[snip]