11:51 a.m.
On Mon, Jan 28, 2019 at 04:13:07PM +0100, Andrea Bolognani wrote:
On Mon, 2019-01-28 at 12:03 +0000, Daniel P. Berrangé wrote:
[...]
> cross-build/arch-config.csv | 8 +++
> cross-build/buildenv-cross.docker.in | 96 ++++++++++++++++++++++++++++
> 3 files changed, 105 insertions(+)
> create mode 100644 cross-build/arch-config.csv
> create mode 100644 cross-build/buildenv-cross.docker.in
You're providing a Dockerfile template and a CSV file containing
the data that should be substituted into it, and it's fairly obvious
how one would go about it, but I would expect you to provide a
script and possibly a Makefile along with this... I assume you just
forgot to commit them? :)
Sigh, yes I forgot the Makefile.
[...]
> +++ b/cross-build/arch-config.csv
> @@ -0,0 +1,8 @@
> +arm64,crossbuild-essential-arm64,aarch64-linux-gnu
> +armel,crossbuild-essential-armel,arm-linux-gnueabi
> +armhf,crossbuild-essential-armhf,arm-linux-gnueabihf
> +mips64el,gcc-mips64el-linux-gnuabi64,mips64el-linux-gnuabi64
> +mips,gcc-mips-linux-gnu,mips-linux-gnu
> +mipsel,gcc-mipsel-linux-gnu,mipsel-linux-gnu
> +ppc64el,crossbuild-essential-ppc64el,powerpc64le-linux-gnu
> +s390x,gcc-multilib-s390x-linux-gnu,s390x-linux-gnu
The file format is not documented, and it really should be.
As for the architecture selection, we should drop armel (it's
unlikely to be part of the next Debian release[1]) and possibly
all the MIPS architectures too? I'm fairly sure nobody is actually
running and testing libvirt on those architectures, so making them
official targets for cross-compilation would be a bit dishonest in
my opinion. Same possibly goes for armhf, but it's less clear-cut
given how many Raspberry Pis are out there.
I don't want to take a stance on popularity of the architectures.
The goal was to provide containers for every architecture that
Debian currently builds libvirt, to ensure that libvirt does not
regress in its ability to build on anything that Debian targets.
We should also use the virArch names instead of the Debian names,
even if that means having additional logic to map between them.
I don't think virArch names offer any benefit, only the pain of
having to remap them to what we actually want to work with.
> +++ b/cross-build/buildenv-cross.docker.in
> @@ -0,0 +1,96 @@
> +#
> +# ::ARCH:: cross-compiler target
> +#
> +FROM debian:stretch-slim
How much smaller is the -slim variant than the regular stretch
image? Because according to the documentation
These tags are an experiment in providing a slimmer base (removing
some extra files that are normally not necessary within containers,
such as man pages and documentation), and are definitely subject
to change.
so unless the savings are very significant, I'd much rather
stick with the regular images.
It depends what you want to measure. The debian:9-slim is ~55 MB
while debian:9 is ~100MB (varies per arch). IOW, the -slim variant
is half the size.
Once you add in the libvirt build deps though this difference is
significantly reduced, as the overall libvirt image is around
1000 MB for debian:9 vs 950 MB for debian:9-slim
> +# First some common native binaries. Any program that the
> +# build will execute needs to have a native binary package
> +# installed. We don't want to rely on qemu-user emulation
> +# for executing non-native binaries as that is slow & flaky
> +RUN DEBIAN_FRONTEND=noninteractive \
> + apt-get install -y --no-install-recommends \
I never considered it until now, but we might want to use
DEBIAN_FRONTEND=noninteractive and --no-install-recommends in our
existing Debian/Ubuntu Dockerfiles as well :)
Yes, we should.
[...]
> + qemu-system-x86 \
Based on what you wrote just a few lines above, QEMU shouldn't be
necessary, so why are you dragging it in?
The comments above were about the qemu userspace emulators,
while this is the system emulator. configure.ac checks for
existance of qemu-system-x86, though this is merely to
warn you if you try to build a QEMU version that needs QMP
while not having yajl installed. So that's not really
required. We should in fact update that check in libvirt.git
really since we mandate yajl for QEMU now, thre's no need
to check QEMU versions.
> + xfslibs-dev:::ARCH:: \
> + libssh-dev:::ARCH:: \
> + libgnutls28-dev:::ARCH::
How did you come up with this list of packages, anyway? It doesn't
match the one in buildenv-debian-9.Dockerfile from the
libvirt-dockerfiles repository.
It comes from the list of build requires listed for the
debian source package
https://packages.debian.org/source/sid/libvirt
On a more general note, we shouldn't have such a list at all:
the
source of truth for build dependencies are the YAML files in
guests/vars/, and anything that needs it should obtain it from
there.
Which leads me to an even more general point: this should be part
of lcitool instead of its own thing. We already have (admittedly
not great) code to generate Dockerfiles in there; cleaning it up
and extending it so that it can support this additional variant of
the same idea shouldn't be too difficult.
It was not entirely straightforward, as it turns out we had
some bugs in our existing package set that caused conflicts
with cross-arch installs, but I managed to resolve this.
> +# Tell libvirt which architecture we want to target
> +ENV LIBVIRT_CONFIGURE_OPTS "--host=::ABI:: --build=x86_64-linux-gnu
--target=::ABI::"
> +
> +# Tell pkg-config where to find the non-native .pc files
> +ENV PKG_CONFIG_LIBDIR=/usr/lib/::ABI::/pkgconfig
I really don't like injecting this much environment into the
container. Can we limit it to a single $ABI variable, or perhaps
even store it on disk as, I don't know, /root/abi or something?
Either way, we could pick up the information and prepare the above
environment as part of the build process, eg. on the libvirt side.
I don't really see any downside to using these env vars as is.
This is pretty much a standard use for use of docker's ENV feature
and makes it easy to use these containers in the correct manner.
Regards,
Daniel
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