Build Qt5 cross-builder with raspbian sysroot: compiling with the sysroot (continued)

Lite extra ball, from
Lite extra ball, from

This is part of a series of posts on compiling a custom version of Qt5 in order to develop for both amd64 and a Raspberry Pi.

The previous rounds of attempts ended in one issue too many to investigate in the allocated hourly budget.

Andreas Gruber wrote:

Long story short, a fast solution for the issue with EGLSetBlobFuncANDROID is to remove libraspberrypi-dev from your sysroot and do a full rebuild. There will be some changes to the configure results, so please review them - if they are relevant for you - before proceeding with your work.

That got me unstuck! dpkg --purge libraspberrypi-dev in the sysroot, and we're back in the game.

While Qt5's build has proven extremely fragile, I was surprised that some customization from Raspberry Pi hadn't yet broken something. In the end, they didn't disappoint.

More i386 issues

The run now stops with a new 32bit issue related to v8 snapshots:

qt-everywhere-src-5.15.0/qtwebengine/src/core/release$ /usr/bin/g++ -pie -Wl,--fatal-warnings -Wl,--build-id=sha1 -fPIC -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,-z,defs -Wl,--as-needed -m32 -pie -Wl,--disable-new-dtags -Wl,-O2 -Wl,--gc-sections -o "v8_snapshot/mksnapshot" -Wl,--start-group @"v8_snapshot/mksnapshot.rsp"  -Wl,--end-group  -ldl -lpthread -lrt -lz
/usr/bin/ld: skipping incompatible //usr/lib/x86_64-linux-gnu/ when searching for -lz
/usr/bin/ld: skipping incompatible //usr/lib/x86_64-linux-gnu/libz.a when searching for -lz
/usr/bin/ld: cannot find -lz
collect2: error: ld returned 1 exit status

Attempted solution: apt install zlib1g-dev:i386.

Alternative solution (untried): configure Qt5 with -no-webengine-v8-snapshot.

It builds!

Installation paths

Now it tries to install files into debian/tmp/home/build/sysroot/opt/qt5custom-armhf/.

I realise that I now need to package the sysroot itself, both as a build-dependency of the Qt5 cross-compiler, and as a runtime dependency of the built cross-builder.


The current work in progress, patches, and all, is at

It blows my mind how ridiculously broken is the Qt5 cross-compiler build, for a use case that, looking at how many people are trying, seems to be one of the main ones for the cross-builder.