Re: How do you represent a host gcc and a cross gcc in lcitool?

[Alistair Francis <alistair23@gmail.com>]

On Fri, Jun 23, 2023 at 8:29 PM Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Alistair Francis <alistair23@gmail.com> writes:
>
> > On Thu, Jun 1, 2023 at 4:58 AM Alex Bennée <alex.bennee@linaro.org> wrote:
> >>
> >>
> >> Brian Cain <bcain@quicinc.com> writes:
> >>
> >> >> -----Original Message-----
> >> >> From: Alex Bennée <alex.bennee@linaro.org>
> >> >> Sent: Wednesday, May 31, 2023 6:24 AM
> >> >> To: Daniel P.Berrangé <berrange@redhat.com>
> >> >> Cc: qemu-devel <qemu-devel@nongnu.org>; Michael Tokarev
> >> >> <mjt@tls.msk.ru>; Erik Skultety <eskultet@redhat.com>; Brian Cain
> >> >> <bcain@quicinc.com>; Palmer Dabbelt <palmer@dabbelt.com>; Alistair Francis
> >> >> <alistair.francis@wdc.com>; Bin Meng <bin.meng@windriver.com>
> >> >> Subject: How do you represent a host gcc and a cross gcc in lcitool?
> >> >>
> >> >> WARNING: This email originated from outside of Qualcomm. Please be wary of
> >> >> any links or attachments, and do not enable macros.
> >> >>
> >> >> Hi,
> >> >>
> >> >> While trying to convert the debian-riscv64-cross docker container to an
> >> >> lcitool based one I ran into a problem building QEMU. The configure step
> >> >> fails because despite cross compiling we still need a host compiler to
> >> >> build the hexagon codegen tooling.
> >> >
> >> > I thought we'd fixed this container definition so that we only
> >> > downloaded the hexagon toolchain instead? Do we really need a host
> >> > compiler for that container build?
> >> >
> >> > Or am I misunderstanding and you're referring to features required to
> >> > support idef parser? Does "hexagon codegen" refer to hexagon's TCG
> >> > generation or hexagon code itself (required by tests/tcg)?
> >>
> >> I think so:
> >>
> >> #
> >> #  Step 1
> >> #  We use a C program to create semantics_generated.pyinc
> >> #
> >> gen_semantics = executable(
> >>     'gen_semantics',
> >>     'gen_semantics.c',
> >>     native: true, build_by_default: false)
> >>
> >> semantics_generated = custom_target(
> >>     'semantics_generated.pyinc',
> >>     output: 'semantics_generated.pyinc',
> >>     command: [gen_semantics, '@OUTPUT@'],
> >> )
> >> hexagon_ss.add(semantics_generated)
> >>
> >>
> >> >
> >> >> After scratching my head for a while I discovered we did have host GCC's
> >> >> in our cross images despite there being no explicit request for them in
> >> >> the docker description. It turned out that the gcovr requirement pulled
> >> >> in lcov which itself had a dependency on gcc. However this is a bug:
> >> >>
> >> >>   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=987818
> >> >>
> >> >> which has been fixed in bookworm (and of course sid which is the only
> >> >> way we can get a riscv64 build of QEMU at the moment). Hence my hacky
> >> >> attempts to get gcc via side effect of another package failed.
> >> >>
> >> >> Hence the question in $SUBJECT. I tried to add a mapping to lcitool for
> >> >> a pseudo hostgcc package:
> >> >>
> >> >> +  hostgcc:
> >> >> +    default: gcc
> >> >> +    pkg:
> >> >> +    MacOS:
> >> >> +    cross-policy-default: skip
> >> >>
> >> >> however this didn't work. Do we need a new mechanism for this or am I
> >> >> missing a way to do this?
> >> >>
> >> >> RiscV guys,
> >> >>
> >> >> It's clear that relying on Debian Sid for the QEMU cross build for RiscV
> >> >> is pretty flakey. Are you guys aware of any other distros that better
> >> >> support cross compiling to a riscv64 target or is Debian still the best
> >> >> bet? Could you be persuaded to build a binary docker image with the
> >> >> cross compilers and libraries required for a decent cross build as an
> >> >> alternative?
> >
> > It's probably not very helpful, but I find Arch based distros to be
> > the best bet for this.
>
> I've never tried arch under docker, isn't it just as much of a moving
> target?

I haven't really tried Arch under Docker. I agree that it is a fast
moving target. I guess it's up for debate if it's too much churn or
not

Would a working Arch image be helpful with lcitool?

>
> > Are you still looking for a Docker image? I could try and get
> > something working
>
> Yes, although I have converted debian-riscv64-cross to lcitool and had
> it working sid has since broken. Are there any pushes to have riscv as a
> first class distro citizen soon or is stuff still in the early ports
> stage?

There are pushes. I thought RISC-V was progressing towards first class
distro support, but it seems to have stalled recently.

I actually thought you could cross compile with Debian bullseye, yet
alone bookworm, has someone tried? Otherwise I can give it a crack

Alistair

>
> --
> Alex Bennée
> Virtualisation Tech Lead @ Linaro