mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-15 08:44:14 +08:00
a0d1c951ef
As Documentation/kbuild/llvm.rst implies, building the kernel with a full set of LLVM tools gets very verbose and unwieldy. Provide a single switch LLVM=1 to use Clang and LLVM tools instead of GCC and Binutils. You can pass it from the command line or as an environment variable. Please note LLVM=1 does not turn on the integrated assembler. You need to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the integrated assembler, I think we can make it default. We discussed what we need, and we agreed to go with a simple boolean flag that switches both target and host tools: https://lkml.org/lkml/2020/3/28/494 https://lkml.org/lkml/2020/4/3/43 Some items discussed, but not adopted: - LLVM_DIR When multiple versions of LLVM are installed, I just thought supporting LLVM_DIR=/path/to/my/llvm/bin/ might be useful. CC = $(LLVM_DIR)clang LD = $(LLVM_DIR)ld.lld ... However, we can handle this by modifying PATH. So, we decided to not do this. - LLVM_SUFFIX Some distributions (e.g. Debian) package specific versions of LLVM with naming conventions that use the version as a suffix. CC = clang$(LLVM_SUFFIX) LD = ld.lld(LLVM_SUFFIX) ... will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc., but the suffixed versions in /usr/bin/ are symlinks to binaries in /usr/lib/llvm-#/bin/, so this can also be handled by PATH. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
270 lines
7.4 KiB
ReStructuredText
270 lines
7.4 KiB
ReStructuredText
======
|
|
Kbuild
|
|
======
|
|
|
|
|
|
Output files
|
|
============
|
|
|
|
modules.order
|
|
-------------
|
|
This file records the order in which modules appear in Makefiles. This
|
|
is used by modprobe to deterministically resolve aliases that match
|
|
multiple modules.
|
|
|
|
modules.builtin
|
|
---------------
|
|
This file lists all modules that are built into the kernel. This is used
|
|
by modprobe to not fail when trying to load something builtin.
|
|
|
|
modules.builtin.modinfo
|
|
-----------------------
|
|
This file contains modinfo from all modules that are built into the kernel.
|
|
Unlike modinfo of a separate module, all fields are prefixed with module name.
|
|
|
|
|
|
Environment variables
|
|
=====================
|
|
|
|
KCPPFLAGS
|
|
---------
|
|
Additional options to pass when preprocessing. The preprocessing options
|
|
will be used in all cases where kbuild does preprocessing including
|
|
building C files and assembler files.
|
|
|
|
KAFLAGS
|
|
-------
|
|
Additional options to the assembler (for built-in and modules).
|
|
|
|
AFLAGS_MODULE
|
|
-------------
|
|
Additional assembler options for modules.
|
|
|
|
AFLAGS_KERNEL
|
|
-------------
|
|
Additional assembler options for built-in.
|
|
|
|
KCFLAGS
|
|
-------
|
|
Additional options to the C compiler (for built-in and modules).
|
|
|
|
CFLAGS_KERNEL
|
|
-------------
|
|
Additional options for $(CC) when used to compile
|
|
code that is compiled as built-in.
|
|
|
|
CFLAGS_MODULE
|
|
-------------
|
|
Additional module specific options to use for $(CC).
|
|
|
|
LDFLAGS_MODULE
|
|
--------------
|
|
Additional options used for $(LD) when linking modules.
|
|
|
|
HOSTCFLAGS
|
|
----------
|
|
Additional flags to be passed to $(HOSTCC) when building host programs.
|
|
|
|
HOSTCXXFLAGS
|
|
------------
|
|
Additional flags to be passed to $(HOSTCXX) when building host programs.
|
|
|
|
HOSTLDFLAGS
|
|
-----------
|
|
Additional flags to be passed when linking host programs.
|
|
|
|
HOSTLDLIBS
|
|
----------
|
|
Additional libraries to link against when building host programs.
|
|
|
|
KBUILD_KCONFIG
|
|
--------------
|
|
Set the top-level Kconfig file to the value of this environment
|
|
variable. The default name is "Kconfig".
|
|
|
|
KBUILD_VERBOSE
|
|
--------------
|
|
Set the kbuild verbosity. Can be assigned same values as "V=...".
|
|
|
|
See make help for the full list.
|
|
|
|
Setting "V=..." takes precedence over KBUILD_VERBOSE.
|
|
|
|
KBUILD_EXTMOD
|
|
-------------
|
|
Set the directory to look for the kernel source when building external
|
|
modules.
|
|
|
|
Setting "M=..." takes precedence over KBUILD_EXTMOD.
|
|
|
|
KBUILD_OUTPUT
|
|
-------------
|
|
Specify the output directory when building the kernel.
|
|
|
|
The output directory can also be specified using "O=...".
|
|
|
|
Setting "O=..." takes precedence over KBUILD_OUTPUT.
|
|
|
|
KBUILD_EXTRA_WARN
|
|
-----------------
|
|
Specify the extra build checks. The same value can be assigned by passing
|
|
W=... from the command line.
|
|
|
|
See `make help` for the list of the supported values.
|
|
|
|
Setting "W=..." takes precedence over KBUILD_EXTRA_WARN.
|
|
|
|
KBUILD_DEBARCH
|
|
--------------
|
|
For the deb-pkg target, allows overriding the normal heuristics deployed by
|
|
deb-pkg. Normally deb-pkg attempts to guess the right architecture based on
|
|
the UTS_MACHINE variable, and on some architectures also the kernel config.
|
|
The value of KBUILD_DEBARCH is assumed (not checked) to be a valid Debian
|
|
architecture.
|
|
|
|
ARCH
|
|
----
|
|
Set ARCH to the architecture to be built.
|
|
|
|
In most cases the name of the architecture is the same as the
|
|
directory name found in the arch/ directory.
|
|
|
|
But some architectures such as x86 and sparc have aliases.
|
|
|
|
- x86: i386 for 32 bit, x86_64 for 64 bit
|
|
- sh: sh for 32 bit, sh64 for 64 bit
|
|
- sparc: sparc32 for 32 bit, sparc64 for 64 bit
|
|
|
|
CROSS_COMPILE
|
|
-------------
|
|
Specify an optional fixed part of the binutils filename.
|
|
CROSS_COMPILE can be a part of the filename or the full path.
|
|
|
|
CROSS_COMPILE is also used for ccache in some setups.
|
|
|
|
CF
|
|
--
|
|
Additional options for sparse.
|
|
|
|
CF is often used on the command-line like this::
|
|
|
|
make CF=-Wbitwise C=2
|
|
|
|
INSTALL_PATH
|
|
------------
|
|
INSTALL_PATH specifies where to place the updated kernel and system map
|
|
images. Default is /boot, but you can set it to other values.
|
|
|
|
INSTALLKERNEL
|
|
-------------
|
|
Install script called when using "make install".
|
|
The default name is "installkernel".
|
|
|
|
The script will be called with the following arguments:
|
|
|
|
- $1 - kernel version
|
|
- $2 - kernel image file
|
|
- $3 - kernel map file
|
|
- $4 - default install path (use root directory if blank)
|
|
|
|
The implementation of "make install" is architecture specific
|
|
and it may differ from the above.
|
|
|
|
INSTALLKERNEL is provided to enable the possibility to
|
|
specify a custom installer when cross compiling a kernel.
|
|
|
|
MODLIB
|
|
------
|
|
Specify where to install modules.
|
|
The default value is::
|
|
|
|
$(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
|
|
|
|
The value can be overridden in which case the default value is ignored.
|
|
|
|
INSTALL_MOD_PATH
|
|
----------------
|
|
INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
|
|
relocations required by build roots. This is not defined in the
|
|
makefile but the argument can be passed to make if needed.
|
|
|
|
INSTALL_MOD_STRIP
|
|
-----------------
|
|
INSTALL_MOD_STRIP, if defined, will cause modules to be
|
|
stripped after they are installed. If INSTALL_MOD_STRIP is '1', then
|
|
the default option --strip-debug will be used. Otherwise,
|
|
INSTALL_MOD_STRIP value will be used as the options to the strip command.
|
|
|
|
INSTALL_HDR_PATH
|
|
----------------
|
|
INSTALL_HDR_PATH specifies where to install user space headers when
|
|
executing "make headers_*".
|
|
|
|
The default value is::
|
|
|
|
$(objtree)/usr
|
|
|
|
$(objtree) is the directory where output files are saved.
|
|
The output directory is often set using "O=..." on the commandline.
|
|
|
|
The value can be overridden in which case the default value is ignored.
|
|
|
|
KBUILD_ABS_SRCTREE
|
|
--------------------------------------------------
|
|
Kbuild uses a relative path to point to the tree when possible. For instance,
|
|
when building in the source tree, the source tree path is '.'
|
|
|
|
Setting this flag requests Kbuild to use absolute path to the source tree.
|
|
There are some useful cases to do so, like when generating tag files with
|
|
absolute path entries etc.
|
|
|
|
KBUILD_SIGN_PIN
|
|
---------------
|
|
This variable allows a passphrase or PIN to be passed to the sign-file
|
|
utility when signing kernel modules, if the private key requires such.
|
|
|
|
KBUILD_MODPOST_WARN
|
|
-------------------
|
|
KBUILD_MODPOST_WARN can be set to avoid errors in case of undefined
|
|
symbols in the final module linking stage. It changes such errors
|
|
into warnings.
|
|
|
|
KBUILD_MODPOST_NOFINAL
|
|
----------------------
|
|
KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
|
|
This is solely useful to speed up test compiles.
|
|
|
|
KBUILD_EXTRA_SYMBOLS
|
|
--------------------
|
|
For modules that use symbols from other modules.
|
|
See more details in modules.rst.
|
|
|
|
ALLSOURCE_ARCHS
|
|
---------------
|
|
For tags/TAGS/cscope targets, you can specify more than one arch
|
|
to be included in the databases, separated by blank space. E.g.::
|
|
|
|
$ make ALLSOURCE_ARCHS="x86 mips arm" tags
|
|
|
|
To get all available archs you can also specify all. E.g.::
|
|
|
|
$ make ALLSOURCE_ARCHS=all tags
|
|
|
|
KBUILD_BUILD_TIMESTAMP
|
|
----------------------
|
|
Setting this to a date string overrides the timestamp used in the
|
|
UTS_VERSION definition (uname -v in the running kernel). The value has to
|
|
be a string that can be passed to date -d. The default value
|
|
is the output of the date command at one point during build.
|
|
|
|
KBUILD_BUILD_USER, KBUILD_BUILD_HOST
|
|
------------------------------------
|
|
These two variables allow to override the user@host string displayed during
|
|
boot and in /proc/version. The default value is the output of the commands
|
|
whoami and host, respectively.
|
|
|
|
LLVM
|
|
----
|
|
If this variable is set to 1, Kbuild will use Clang and LLVM utilities instead
|
|
of GCC and GNU binutils to build the kernel.
|