[vlc-devel] Support for Windows on Arm

[Steve Lhomme]

On 2022-09-09 10:52, Martin Storsjö wrote:
> On Fri, 9 Sep 2022, Pierrick Bouvier wrote:
> 
>> On 9/9/22 10:39, Martin Storsjö wrote:
>>> On Fri, 9 Sep 2022, Pierre Lamot wrote:
>>>
>>>>
>>>> On 09/09/2022 10:29, Steve Lhomme wrote:
>>>>> out of the box for Windows ARM. It should build like the other Windows
>>>>> targets except adding `-a aarch64` to build.sh. It should work with
>>>>> the LLVM Dockers we use (or any llvm-mingw build). Not sure there's
>>>>> mingw-w64 for ARM available.
>>>>>
>>>>> There may be some contribs that don't build properly, for example Qt
>>>>> may refuse to build or not understand what's going on. And if it
>>>>> builds it's not
>>>>
>>>> according to your website [1], qt for windows arm requires version 6.2,
>>>> but we only support Qt 5, so this may indeed be a problem if you 
>>>> plan to
>>>> build the UI
>>>
>>> I dunno what that information that website is based on, but with 
>>> upstream
>>> Qt (plain Qt Core) it has worked fine since around Qt 5.11 with
>>> llvm-mingw. Maybe it's based on what they have tested themselves?
>>>
>>> It runs just fine with the Qt backported patches in VLC's contrib, on 
>>> both
>>> the 3.0.x and master branches.
>>>
>>
>> We observed issues with previous version. For instance, with cmake-gui 
>> that is crashing on startup. It's good to know it's working for VLC.
> 
> Ok, that's good to know. FWIW, if there's an issue with older versions 
> but which is fixed in newer ones, it's usually quite straightforward to 
> do a reverse bisect to find out which commit fixed it, and then backport 
> that one to the version of Qt that is used. (VLC carries half a dozen of 
> backported Qt patches, for building the ancient Qt 5.6 with modern 
> compilers.)
> 
>> Officially, Qt is advertising support for Windows on Arm from Qt6 [1], 
>> while Qt5 does not mention it [2]. In more, prebuilt versions are only 
>> available since Qt6. Not every project builds Qt from source ;).
> 
> Well the prebuilt binaries don't really help people in the mingw 
> ecosystem anyway, as those are MSVC only. And in practice I don't know 
> of any more concrete efforts from Qt's side here (but I may have missed 
> something) other than doing regular builds of it. But for sure, newer 
> versions generally do come with more fixes that need to be backported if 
> using older versions.

BTW, I completely forgot that we do have windows ARM 64-bit building in 
our CI already. But Qt is disabled and also mistakenly as a UWP build. I 
can try to change it to a full desktop build and see how it goes.

https://code.videolan.org/videolan/vlc/-/jobs/1134041