uapi: export all headers under uapi directories

Regularly, when a new header is created in include/uapi/, the developer
forgets to add it in the corresponding Kbuild file. This error is usually
detected after the release is out.

In fact, all headers under uapi directories should be exported, thus it's
useless to have an exhaustive list.

After this patch, the following files, which were not exported, are now
exported (with make headers_install_all):
asm-arc/kvm_para.h
asm-arc/ucontext.h
asm-blackfin/shmparam.h
asm-blackfin/ucontext.h
asm-c6x/shmparam.h
asm-c6x/ucontext.h
asm-cris/kvm_para.h
asm-h8300/shmparam.h
asm-h8300/ucontext.h
asm-hexagon/shmparam.h
asm-m32r/kvm_para.h
asm-m68k/kvm_para.h
asm-m68k/shmparam.h
asm-metag/kvm_para.h
asm-metag/shmparam.h
asm-metag/ucontext.h
asm-mips/hwcap.h
asm-mips/reg.h
asm-mips/ucontext.h
asm-nios2/kvm_para.h
asm-nios2/ucontext.h
asm-openrisc/shmparam.h
asm-parisc/kvm_para.h
asm-powerpc/perf_regs.h
asm-sh/kvm_para.h
asm-sh/ucontext.h
asm-tile/shmparam.h
asm-unicore32/shmparam.h
asm-unicore32/ucontext.h
asm-x86/hwcap2.h
asm-xtensa/kvm_para.h
drm/armada_drm.h
drm/etnaviv_drm.h
drm/vgem_drm.h
linux/aspeed-lpc-ctrl.h
linux/auto_dev-ioctl.h
linux/bcache.h
linux/btrfs_tree.h
linux/can/vxcan.h
linux/cifs/cifs_mount.h
linux/coresight-stm.h
linux/cryptouser.h
linux/fsmap.h
linux/genwqe/genwqe_card.h
linux/hash_info.h
linux/kcm.h
linux/kcov.h
linux/kfd_ioctl.h
linux/lightnvm.h
linux/module.h
linux/nbd-netlink.h
linux/nilfs2_api.h
linux/nilfs2_ondisk.h
linux/nsfs.h
linux/pr.h
linux/qrtr.h
linux/rpmsg.h
linux/sched/types.h
linux/sed-opal.h
linux/smc.h
linux/smc_diag.h
linux/stm.h
linux/switchtec_ioctl.h
linux/vfio_ccw.h
linux/wil6210_uapi.h
rdma/bnxt_re-abi.h

Note that I have removed from this list the files which are generated in every
exported directories (like .install or .install.cmd).

Thanks to Julien Floret <julien.floret@6wind.com> for the tip to get all
subdirs with a pure makefile command.

For the record, note that exported files for asm directories are a mix of
files listed by:
 - include/uapi/asm-generic/Kbuild.asm;
 - arch/<arch>/include/uapi/asm/Kbuild;
 - arch/<arch>/include/asm/Kbuild.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Mark Salter <msalter@redhat.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

1 files changed, 41 insertions, 25 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 37b525d..b9f7ca4 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -44,10 +44,12 @@ This document describes the Linux kernel Makefiles.
 	   --- 6.11 Post-link pass
 
 	=== 7 Kbuild syntax for exported headers
-		--- 7.1 header-y
+		--- 7.1 no-export-headers
 		--- 7.2 genhdr-y
 		--- 7.3 generic-y
 		--- 7.4 generated-y
+		--- 7.5 mandatory-y
+		--- 7.6 subdir-y
 
 	=== 8 Kbuild Variables
 	=== 9 Makefile language
@@ -1235,7 +1237,7 @@ When kbuild executes, the following steps are followed (roughly):
 	that may be shared between individual architectures.
 	The recommended approach how to use a generic header file is
 	to list the file in the Kbuild file.
-	See "7.4 generic-y" for further info on syntax etc.
+	See "7.3 generic-y" for further info on syntax etc.
 
 --- 6.11 Post-link pass
 
@@ -1262,37 +1264,30 @@ The pre-processing does:
 - drop include of compiler.h
 - drop all sections that are kernel internal (guarded by ifdef __KERNEL__)
 
-Each relevant directory contains a file name "Kbuild" which specifies the
-headers to be exported.
-See subsequent chapter for the syntax of the Kbuild file.
-
-	--- 7.1 header-y
-
-	header-y specifies header files to be exported.
-
-		Example:
-			#include/linux/Kbuild
-			header-y += usb/
-			header-y += aio_abi.h
+All headers under include/uapi/, include/generated/uapi/,
+arch/<arch>/include/uapi/asm/ and arch/<arch>/include/generated/uapi/asm/
+are exported.
 
-	The convention is to list one file per line and
-	preferably in alphabetic order.
+A Kbuild file may be defined under arch/<arch>/include/uapi/asm/ and
+arch/<arch>/include/asm/ to list asm files coming from asm-generic.
+See subsequent chapter for the syntax of the Kbuild file.
 
-	header-y also specifies which subdirectories to visit.
-	A subdirectory is identified by a trailing '/' which
-	can be seen in the example above for the usb subdirectory.
+	--- 7.1 no-export-headers
 
-	Subdirectories are visited before their parent directories.
+	no-export-headers is essentially used by include/uapi/linux/Kbuild to
+	avoid exporting specific headers (e.g. kvm.h) on architectures that do
+	not support it. It should be avoided as much as possible.
 
 	--- 7.2 genhdr-y
 
-	genhdr-y specifies generated files to be exported.
-	Generated files are special as they need to be looked
-	up in another directory when doing 'make O=...' builds.
+	genhdr-y specifies asm files to be generated.
 
 		Example:
-			#include/linux/Kbuild
-			genhdr-y += version.h
+			#arch/x86/include/uapi/asm/Kbuild
+			genhdr-y += unistd_32.h
+			genhdr-y += unistd_64.h
+			genhdr-y += unistd_x32.h
+
 
 	--- 7.3 generic-y
 
@@ -1334,6 +1329,27 @@ See subsequent chapter for the syntax of the Kbuild file.
 			#arch/x86/include/asm/Kbuild
 			generated-y += syscalls_32.h
 
+	--- 7.5 mandatory-y
+
+	mandatory-y is essentially used by include/uapi/asm-generic/Kbuild.asm
+	to define the minimun set of headers that must be exported in
+	include/asm.
+
+	The convention is to list one subdir per line and
+	preferably in alphabetic order.
+
+	--- 7.6 subdir-y
+
+	subdir-y may be used to specify a subdirectory to be exported.
+
+		Example:
+			#arch/cris/include/uapi/asm/Kbuild
+			subdir-y += ../arch-v10/arch/
+			subdir-y += ../arch-v32/arch/
+
+	The convention is to list one subdir per line and
+	preferably in alphabetic order.
+
 === 8 Kbuild Variables
 
 The top Makefile exports the following variables: