On Tuesday (March 26, 2019), Valve released Proton 4.2, a new update to their Steam Play
compatibility layer based on Wine 4.2. The previous major version of Proton was
based on Wine 3.16.
As with
CodeWeavers's own projects, the strong preference for work going
into Proton is to also get the changes into upstream Wine. There are many benefits
to this. First, all Wine users will benefit from these fixes, whether they are
end users of Wine itself,
CrossOver users, or users of any other Wine fork.
There are also benefits for the maintainers of Proton. For example, upstreaming
patches helps prevent regressions, thanks to Wine's extensive test suite; it
lowers the maintenance burden, as there are fewer changes to move between Wine
versions; it ensures code quality, since patches to Wine are reviewed by the
Wine community; and it widens the pool of users to test, since Wine is used in
many, many places other than Proton.
Proton 3.16-8 has 380 commits on top of Wine 3.16. After rebasing onto Wine
4.2, there are 214 commits. That means that 166 patches from the 3.16 branch
have either been upstreamed, or are otherwise no longer needed going forward.
In addition, a lot of work we have done for Wine 4.2 never got pulled back into
Proton 3.16.
Let's take a look at how upstream Wine has improved thanks to Valve's
sponsored work on Wine. Below is a list of changes to upstream Wine that were
made in order to improve games running in Proton.
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