[igt-dev] [PATCH i-g-t] docs/cross-building.txt: add documentation about cross-builds

[Kamil Konieczny]

Hi Mauro,

On 2023-09-14 at 17:55:44 +0200, Mauro Carvalho Chehab wrote:
> From: Mauro Carvalho Chehab <mchehab at kernel.org>
> 
> Cross-building IGT is not too trivial, as one needs to prepare
> a sysroot directory containing not only glibc, but also other
---------------------------------------------- ^^^^^
s/, but/ but/

> libraries. Yet, such kind of builds are sometimes desired.
-----------------------------------------------------------^
> So, document how to do that.
s/. So, document/ so I documented/
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab at kernel.org>
> ---
>  docs/cross-building.txt | 73 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 73 insertions(+)
>  create mode 100644 docs/cross-building.txt
> 
> diff --git a/docs/cross-building.txt b/docs/cross-building.txt
> new file mode 100644
> index 000000000000..52aa5c361de3
> --- /dev/null
> +++ b/docs/cross-building.txt
> @@ -0,0 +1,73 @@
> +Producing an IGT library for another architecture
------------------- ^^^^^^^
s/library for/for/

> +=================================================
> +

Could you also add here what packets you installed on Fedora?
Any other arm64 headers/libs needed?

> +Meson requires an extra file to do non-native builds. This is passed
> +via --cross-file parameter to it.
> +
> +Such file contains the configuration used to do a cross-compilation build.
> +As such, it contains:
> +
> +- the host machine data, which defines the system and architecture from
> +  the native OS.
> +  At the example below, the native OS is Linux, x86_64 architecture.
> +- the target machine data, containing the target architecture.
> +  At the example below, the target is aarch64 (arm 64 bits architecture).
> +- the sysroot path, where IGT dependent libraries were compiled for a given
> +  architecture.
> +  This can be obtained by either cross-building a distribution using
> +  Yocto, buildroot or similar, or by copying the system root from
> +  an install for the desired architecture, after installing the IGT
> +  needed library dependencies.
> +
> +  At the example below, the libraries are stored under /aarch64-sysroot.
> +
> +  Please notice that the binaries may require some extra libraries used
> +  for cross-compiling. One needs to copy them from the native cross-compiler
> +  toolchain. In the case of Fedora, such files are located  under
> +  /usr/aarch64-linux-gnu/sys-root/ (for aarch64 architecture).
> +
> +Preparing for cross compilation is done by calling meson with the
> +cross-compilation config file name:
> +
> +	meson --cross-file arm64_cross.txt arm64
-------------------------------------- ^^^^^
This should be 'build'

> +
> +The actual compilation can then be done using ninja:
> +
> +	ninja -C arm64
------------ ^^^^^
Same here, use build:

ninja -C build

Option -C changes path before running next actions.

Regards,
Kamil

> +
> +Please notice that some parts of the IGT build are disabled during
> +cross-compilation, like testlist file creation and documentation,
> +as such steps depend on running the generated code at the native
> +machine.
> +
> +arm64_cross.txt example
> +-----------------------
> +
> +[constants]
> +sysroot = '/aarch64-sysroot'
> +common_args = ['--sysroot=' + sysroot]
> +
> +[properties]
> +sys_root = sysroot
> +c_args = common_args
> +c_link_args = common_args
> +pkg_config_libdir = [sysroot + '/usr/lib64/pkgconfig', sysroot +'/usr/share/pkgconfig', sysroot +'/usr/local/lib/pkgconfig']
> +
> +[binaries]
> +c = '/usr/bin/aarch64-linux-gnu-gcc'
> +ar = '/usr/bin/aarch64-linux-gnu-gcc-ar'
> +ld = '/usr/bin/aarch64-linux-gnu-ld'
> +strip = '/usr/bin/aarch64-linux-gnu-strip'
> +pkgconfig = 'pkg-config'
> +
> +[host_machine]
> +system = 'linux'
> +cpu_family = 'x86_64'
> +cpu = 'x86_64'
> +endian = 'little'
> +
> +[target_machine]
> +system = 'linux'
> +cpu_family = 'aarch64'
> +cpu = 'aarch64'
> +endian = 'little'
> -- 
> 2.41.0
>