Re: [PATCH 4/7] docs/devel: add information on how to setup build environments

["Alex Bennée" <alex.bennee@linaro.org>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> On Mon, Nov 18, 2024 at 09:23:54AM -0800, Pierrick Bouvier wrote:
>> MacOS and Linux are straightforward, but Windows needs a bit more
>> details.
>> 
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>>  docs/about/build-platforms.rst   |   4 +-
>>  docs/devel/build-environment.rst | 114 +++++++++++++++++++++++++++++++
>>  docs/devel/index-build.rst       |   1 +
>>  3 files changed, 118 insertions(+), 1 deletion(-)
>>  create mode 100644 docs/devel/build-environment.rst
>> 
<snip>
>> +Fedora
>> +++++++
>> +
>> +::
>> +
>> +    sudo dnf update && sudo dnf builddep qemu
>> +
>> +Debian/Ubuntu
>> ++++++++++++++
>> +
>> +You first need to enable `Sources List <https://wiki.debian.org/SourcesList>`_.
>> +Then, use apt to install dependencies:
>> +
>> +::
>> +
>> +    sudo apt update && sudo apt build-dep qemu
>> +
>> +MacOS
>> +-----
>> +
>> +You first need to install `Homebrew <https://brew.sh/>`_. Then, use it to
>> +install dependencies:
>> +
>> +::
>> +
>> +    brew update && brew install $(brew deps --include-build qemu)
>
>
> The downside in recommending the 'build dep' approach is that it misses
> out on deps that have been newly introduced in qemu.git, since whatever
> old version of QEMU the distros are shipping.  It also misses deps for
> any features the distro vendor has decided to exclude.
>
> Can we put a caveat describing this limitation at the top, so that users
> have pointer if things don't quite go the way we expected.

At a recent QEMU workshop I presented I pointed to lcitool as a way to
list the minimal dependencies QEMU needs:

  ./tests/lcitool/libvirt-ci/bin/lcitool variables -f yaml debian-12 ./tests/lcitool/projects/qemu-minimal.yml

It wouldn't be the hardest thing to extend lcitool to generate a pkg
install line instead of a list. Although I notice it fails with the full
set of dependancies:

  ✗  ./tests/lcitool/libvirt-ci/bin/lcitool -d tests/lcitool variables -f shell debian-12 ./tests/lcitool/projects/qemu.yml
  Package generic name resolution error: Package libcbor not present in mappings

I note there is already an "install" action but I'm wary of what it does.

>
>> +
>> +Windows
>> +-------
>> +
>> +You first need to install `MSYS2 <https://www.msys2.org/>`_.
>> +MSYS2 offers `different environments <https://www.msys2.org/docs/environments/>`_.
>> +x86_64 environments are based on GCC, while aarch64 is based on Clang.
>> +
>> +We recommend to use MINGW64 for windows-x86_64 and CLANGARM64 for windows-aarch64
>> +(only available on windows-aarch64 hosts).
>
> Does CLANGARM64 really work with QEMU ?   We go out of our way to actively
> block the use of CLang for Windows because of its lack of support for
> 'gcc_struct' attributes, so I would have expected it to fail
>
>> +
>> +Then, you can open a windows shell, and enter msys2 env using:
>> +
>> +::
>> +
>> +    c:/msys64/msys2_shell.cmd -defterm -here -no-start -mingw64
>> +    # Replace -ucrt64 by -clangarm64 or -ucrt64 for other environments.
>> +
>> +MSYS2 package manager does not offer a built-in way to install build
>> +dependencies. You can start with this list of packages using pacman:
>> +
>
> With regards,
> Daniel

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro