Introduction to QtWebEngine
QtWebEngine integrates
chromium's web capabilities into
Qt. It ships with its own copy of ninja which it uses for the build
if it cannot find a system copy, and various copies of libraries
from ffmpeg, icu, libvpx, and zlib (including libminizip) which
have been forked by the chromium
developers.
This package and browsers using it may be useful if you need to use
a website designed for google chrome, or chromium, browsers.
![[Warning]](../images/warning.png)
Warning
QtWebEngine uses a forked copy of chromium, and is therefore
vulnerable to many issues found there. The Qt developers seem to
fork a newer version for minor Qt versions, but because chromium
moves to newer versions very often, by the time the Qt developers
get a forked version to pass their extended tests it is always an
old version and security fixes from chromium (some of which have
a CVE number) can take several months to appear in a QtWebengine
release, even if the severity has been rated as Critical.
Therefore, you should be wary of using QtWebEngine in a sensitive
context and should always update to the next release as soon as
it appears in this book, even if is not flagged as a Security
Update. Identifying which vulnerabilities have been fixed in a
particular release requires pulling the appropriate 'based-NNN'
branch just before the previous and current releases and is often
impractical. Reports of fixed QTBUG items do not seem to be
available and there is not any documentation in the tarball for
changes after the qt-5 versions.
![[Note]](../images/note.png)
Note
Development versions of BLFS may not build or run some packages
properly if LFS or dependencies have been updated since the most
recent stable versions of the books.
Warning
By default, ninja will use all online CPUs +2 (if at least 4
exist), even if they are not available to the current task
because the build terminal has been restricted with 'taskset'. In
BLFS, this package takes more time to build than any other. In
one example, the build of this package crashed at about the 90
percent point due to an out of memory problem on a system with 24
cores and 32 GB of memory.
To work around this, see the Command Explanations below.
Package Information
qtwebengine Dependencies
Required
Cups-2.4.11, html5lib-1.1, nodejs-20.18.0, nss-3.105, pciutils-3.13.0, and Qt-6.8.0
Recommended
Note
If these packages are not installed, the build process will
compile and install its own (perhaps older) version, with the
side effect of increasing build and installed disk space and
build time.
either alsa-lib-1.2.12 or PulseAudio-17.0 (or both), FFmpeg-7.1,
ICU-75.1, libwebp-1.4.0,
libxslt-1.1.42, and Opus-1.5.2
Optional
libevent-2.1.12, MIT
Kerberos V5-1.21.3, pipewire-1.2.5, Poppler-24.09.0, jsoncpp,
libsrtp, snappy
Installation of qtwebengine
First, fix a build failure that occurs because the BLFS build of
ffmpeg does not use OpenH264:
sed -e '189 s/=/& false/' \
-e '190 d' \
-i.orig src/3rdparty/chromium/third_party/webrtc/webrtc.gni
Install qtwebengine by running the
following commands:
mkdir build &&
cd build &&
cmake -D CMAKE_MESSAGE_LOG_LEVEL=STATUS \
-D QT_FEATURE_webengine_system_ffmpeg=ON \
-D QT_FEATURE_webengine_system_icu=ON \
-D QT_FEATURE_webengine_system_libevent=ON \
-D QT_FEATURE_webengine_proprietary_codecs=ON \
-D QT_FEATURE_webengine_webrtc_pipewire=ON \
-D QT_BUILD_EXAMPLES_BY_DEFAULT=OFF \
-G Ninja .. &&
ninja
This package does not come with a test suite.
Now, as the root user:
ninja install
Command Explanations
CMAKE_MESSAGE_LOG_LEVEL=STATUS:
Output interesting messages that project users might be interested
in. Ideally these should be concise, no more than a single line,
but still informative.
QT_FEATURE_webengine_system_*:
Specify what external packages the system should use.
QT_BUILD_EXAMPLES_BY_DEFAULT=OFF: Do
not build examples by default.
NINJAJOBS=4 make: If you patched system
ninja in LFS to recognize the NINJAJOBS environment variable, this
command will run system ninja with the specified number of jobs
(i.e. 4). There are several reasons why you might want to use
options like this this:
-
Building on a subset of CPUs allows measuring the build time
for a smaller number of processors, and/or running other
CPU-intensive tasks at the same time. For an editor on a
machine with a lot of CPUs, trying to measure the build time
for a 4-CPU machine, NINJAJOBS=4
make will give a reasonable approximation (there is a
short period where N+2 python and node jobs run).
-
On a machine with only 4 CPUs online, the default of
scheduling N+2 jobs for qtwebengine is slower by between 3%
and 7%, probably because of the size of the C++ files and
their many includes and templates. Therefore, if in doubt set
NINJAJOBS to the number of CPUs.
-
Reducing the number of cores being used on long running, CPU
intensive packages may alleviate heat problems.
-
Reducing the number of cores will prevent potential
out-of-memory problems on systems that do not have enough
memory (or swap) when all cores are active. A suggested
approach is to limit the number of cores to about one core
for each 1.5 GB of combined RAM and swap space.
Configuring QtWebEngine
Configuration Information
If you are upgrading from an older minor version of this
application, for some webpages to load you may need to clear the
browser caches, e.g. for
falkon they will be found in
~/.cache/falkon/. You will need to
do this if the browser starts to render the page and then changes
to a blank tab with a message that something went wrong, and a
button to Retry. Even after removing the old caches, you may need
to retry a few times for each affected tab.
If a browser using this package fails to run and when run from a
term it reports 'Trace/breakpoint trap' that is probably a kernel
configuration issue - there is no need to rebuild QtWebEngine,
see the next section, recompile the kernel and reboot to the new
kernel.
Kernel
Configuration
This package does not require any of the optional kernel namespace
items, but if User namespace is enabled (as
happens in some unit files, for hardening) PID namespace
must also be enabled. In that case enable the following options in
the kernel configuration and recompile the kernel if necessary:
General setup --->
-*- Namespaces support ---> [NAMESPACES]
# Enable or disable *both* of them:
[ /*] User namespace [USER_NS]
[ /*] PID Namespaces [PID_NS]