summaryrefslogtreecommitdiff
path: root/Documentation/kbuild/makefiles.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/kbuild/makefiles.txt')
-rw-r--r--Documentation/kbuild/makefiles.txt74
1 files changed, 31 insertions, 43 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 9b9c4797fc55..e18daca65ccd 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -44,11 +44,11 @@ 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 destination-y
- --- 7.4 generic-y
- --- 7.5 generated-y
+ --- 7.3 generic-y
+ --- 7.4 generated-y
+ --- 7.5 mandatory-y
=== 8 Kbuild Variables
=== 9 Makefile language
@@ -1236,7 +1236,7 @@ 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
@@ -1263,53 +1263,32 @@ 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/ and arch/<arch>/include/generated/uapi/
+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 destination-y
- When an architecture has a set of exported headers that needs to be
- exported to a different directory destination-y is used.
- destination-y specifies the destination directory for all exported
- headers in the file where it is present.
-
- Example:
- #arch/xtensa/platforms/s6105/include/platform/Kbuild
- destination-y := include/linux
-
- In the example above all exported headers in the Kbuild file
- will be located in the directory "include/linux" when exported.
-
- --- 7.4 generic-y
+ --- 7.3 generic-y
If an architecture uses a verbatim copy of a header from
include/asm-generic then this is listed in the file
@@ -1336,7 +1315,7 @@ See subsequent chapter for the syntax of the Kbuild file.
Example: termios.h
#include <asm-generic/termios.h>
- --- 7.5 generated-y
+ --- 7.4 generated-y
If an architecture generates other header files alongside generic-y
wrappers, and not included in genhdr-y, then generated-y specifies
@@ -1349,6 +1328,15 @@ 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.
+
=== 8 Kbuild Variables
The top Makefile exports the following variables: