[PATCH trivial v4] include/uapi/Kbuild: modify comment to provide summary descriptions for Linux UAPI

[Chen Gang <gang.chen@asianux.com>]

UAPI is whole Linux kernel API, it is important enough to get summary
descriptions by comments.

In "include/uapi/Kbuild", "Makefile..." and "non-arch..." comments are
historical, at present, they need be improved.

Also add more explanations for "include/uapi/" in "include/uapi/Kbuild".


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 include/uapi/Kbuild |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/uapi/Kbuild b/include/uapi/Kbuild
index 81d2106..f396115 100644
--- a/include/uapi/Kbuild
+++ b/include/uapi/Kbuild
@@ -1,6 +1,15 @@
 # UAPI Header export list
-# Top-level Makefile calls into asm-$(ARCH)
-# List only non-arch directories below
+#
+# UAPI ("Userspace API") is in "include/uapi/" and "arch/*/include/uapi/",
+# which will be installed to "/usr/include".
+#
+# Linux generic (architecture independent) UAPI is at "include/uapi/".
+# Except "linux/", other current level sub-directories are for compatibility.
+# It will not accept new additional current level sub-directories or files.
+#
+# "Architecture Specific Mechanism" UAPI is at "arch/*/include/uapi/".
+# Each architecture must have "arch/*/include/uapi/asm" sub-directory.
+# If architecture permits, it can content additional sub-directories.
 
 
 header-y += asm-generic/
-- 
1.7.7.6