blob: ee5d3410bd34edfa63b1bef6cc18d290216eeb18 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
[](https://drone.yoedistro.org/kraj/meta-clang)
# meta-clang (a C language family frontend and LLVM compiler backend)
This layer provides [clang/llvm](http://clang.llvm.org/) as alternative to your system
C/C++ compiler for OpenEmbedded or Yocto Project based distributions along with gcc
# Getting Started
```shell
git clone git://github.com/openembedded/openembedded-core.git
cd openembedded-core
git clone git://github.com/openembedded/bitbake.git
git clone git://github.com/kraj/meta-clang.git
$ . ./oe-init-build-env
```
If using poky ( Yocto project reference Distribution )
```shell
git clone https://git.yoctoproject.org/git/poky
cd poky
git clone git://github.com/kraj/meta-clang.git
$ . ./oe-init-build-env
```
Add meta-clang overlay
```
bitbake-layers add-layer ../meta-clang
```
Check `conf/bblayers.conf` to see that meta-clang is added to layer mix e.g.
# Default Compiler Switch
Note that by default gcc will remain the system compiler, however if you wish
clang to be the default compiler then set
```shell
TOOLCHAIN ?= "clang"
```
in `local.conf`, this would now switch default cross-compiler to be clang
you can select clang per recipe too by writing bbappends for them containing
```shell
TOOLCHAIN = "clang"
```
# Default C++ Standard Library Switch
Note that by default clang libc++ is default C++ standard library, however if you wish
to keep GNU libstdc++ to be the default then set
```shell
LIBCPLUSPLUS = ""
```
in `local.conf`.
You can select libstdc++ per package too by writing bbappends for them containing
```shell
LIBCPLUSPLUS_toolchain-clang_pn-<recipe> = ""
```
# Default Compiler Runtime ( Compiler-rt + libc++ )
By default, clang build from meta-clang uses clang runtime ( compiler-rt + libc++ + libunwind ) out of box
However, it is possible to switch to using gcc runtime as default, In order to do that
following settings are needed in site configurations e.g. in `local.conf`
```shell
TOOLCHAIN ?= "clang"
LIBCPLUSPLUS = ""
COMPILER_RT = ""
UNWINDLIB = ""
```
# Removing clang from generated SDK toolchain
clang based cross compiler is automatically included into the generated SDK using `bitbake meta-toolchain` or
`bitbake -cpopulate_sdk <image>` in circumstanced where clang is not expected to be part of SDK, then reset `CLANGSDK`
variable in `local.conf`
```shell
CLANGSDK = ""
```
# Building
Below we build for qemuarm machine as an example
```shell
$ MACHINE=qemuarm bitbake core-image-full-cmdline
```
# Running
```shell
$ runqemu nographic
```
# Limitations
Few components do not build with clang, if you have a component to add to that list
simply add it to conf/nonclangable.inc e.g.
```shell
TOOLCHAIN_pn-<recipe> = "gcc"
```
and OE will start using gcc to cross compile that recipe.
And if a component does not build with libc++, you can add it to `conf/nonclangable.inc` e.g.
```shell
CXX_remove_pn-<recipe>_toolchain-clang = " -stdlib=libc++ "
```
# Dependencies
```shell
URI: git://github.com/openembedded/openembedded-core.git
branch: master
revision: HEAD
URI: git://github.com/openembedded/bitbake.git
branch: master
revision: HEAD
```
# Contributing
You are encouraged to follow Github Pull request workflow
to share changes and following commit message guidelines are recommended [OE patch guidelines](https://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines)
Layer Maintainer: [Khem Raj](<mailto:raj.khem@gmail.com>)
|
