[PATCH v3 2/4] cxl/uapi: Add warning on CXL command enum

[Ira Weiny <ira.weiny@intel.com>]

The CXL command enum is exported to user space and must maintain
backwards compatibility.

Add comment that new defines must be added to the end of the list.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 include/uapi/linux/cxl_mem.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
index c71021a2a9ed..459a3f7f764b 100644
--- a/include/uapi/linux/cxl_mem.h
+++ b/include/uapi/linux/cxl_mem.h
@@ -19,6 +19,10 @@
 #define CXL_MEM_QUERY_COMMANDS _IOR(0xCE, 1, struct cxl_mem_query_commands)
 #define CXL_MEM_SEND_COMMAND _IOWR(0xCE, 2, struct cxl_send_command)
 
+/*
+ * NOTE: New defines must be added to the end of the list to preserve
+ * compatibility because this enum is exported to user space.
+ */
 #define CXL_CMDS                                                          \
 	___C(INVALID, "Invalid Command"),                                 \
 	___C(IDENTIFY, "Identify Command"),                               \

-- 
2.39.1