Build the mips toolchain from source in the build image.

With no cross compiler to install on 26.04, a first stage builds binutils and
gcc with spawn-compiler.sh and the final image copies the result out of it, so
bison, flex, texinfo and two gcc source trees stay behind rather than shipping.
The script only ever ran make single-threaded, hence the JOBS knob, and the
Dockerfile now wants the repository root as its build context in order to reach
it. libgdk-pixbuf2.0-dev and imagemagick-6.q16 are gone from 26.04 as well,
renamed to libgdk-pixbuf-2.0-dev and imagemagick-7.q16; convert still resolves
through the alternatives system, so the icon install is unaffected.

.dockerignore

@@ -0,0 +1,8 @@
+# The build image only needs a couple of scripts out of the tree, so keep the
+# build context from dragging in a full local build.
+.git
+objs/
+bins/
+/pcsx-redux
+/pcsx-redux-tests
+*.AppImage

tools/build/Dockerfile

@@ -1,4 +1,25 @@
 # Dockerfile for ghcr.io/grumpycoders/pcsx-redux-build
+#
+# This one needs the repository root as its build context, as the first stage
+# builds the mips toolchain using tools/linux-mips/spawn-compiler.sh:
+#
+#   docker build -f tools/build/Dockerfile -t ghcr.io/grumpycoders/pcsx-redux-build .
+
+FROM ubuntu:26.04 AS toolchain
+
+ENV DEBIAN_FRONTEND noninteractive
+ENV TZ Etc/GMT
+
+RUN apt update
+RUN apt dist-upgrade -y
+RUN apt install -y make g++ wget bzip2 xz-utils bison flex texinfo
+RUN apt install -y libgmp-dev libmpfr-dev libmpc-dev
+
+ARG JOBS=
+
+WORKDIR /tmp/toolchain
+COPY tools/linux-mips/spawn-compiler.sh .
+RUN JOBS=$JOBS sh spawn-compiler.sh
 
 FROM ubuntu:26.04
 
@@ -16,7 +37,6 @@ RUN apt install -y pkg-config
 
 # Compilers & base libraries
 RUN apt install -y g++
-RUN apt install -y g++-mipsel-linux-gnu
 
 # Development packages
 RUN apt install -y libavcodec-dev
@@ -33,7 +53,7 @@ RUN apt install -y zlib1g-dev
 # CI utilities
 RUN apt install -y curl wget
 RUN apt install -y xvfb
-RUN apt install -y python3-pip python3-setuptools patchelf desktop-file-utils libgdk-pixbuf2.0-dev fakeroot strace
+RUN apt install -y python3-pip python3-setuptools patchelf desktop-file-utils libgdk-pixbuf-2.0-dev fakeroot strace
 RUN apt install -y glibc-tools lcov
 RUN apt install -y file
 
@@ -42,9 +62,13 @@ RUN apt install -y libfuse2t64
 RUN apt install -y fuse
 
 # AppImage tools
-RUN apt install -y imagemagick-6.q16 gtk-update-icon-cache appstream
+RUN apt install -y imagemagick-7.q16 gtk-update-icon-cache appstream
 RUN apt install -y squashfs-tools zip zsync
 
+# The mips toolchain, built from source in the first stage. Ubuntu dropped the
+# mipsel cross compilers, so there's no distribution package to install here.
+COPY --from=toolchain /usr/local /usr/local
+
 WORKDIR /tmp
 RUN wget https://github.com/AppImage/appimagetool/releases/download/continuous/appimagetool-x86_64.AppImage && \
     chmod +x appimagetool-x86_64.AppImage && \

tools/linux-mips/spawn-compiler.sh

@@ -1,17 +1,18 @@
 #!/bin/sh
 #
 # Building gcc from source isn't necessarily an easy task, and it requires
-# a lot of various dependency packages to work properly. The easiest way
-# to use a mips compiler for Linux is still to use a package from your
-# distribution. Nevertheless, here's how to build a working mips compiler
-# that can produce code for the R3000A CPU, granted you have the necessary
-# dependencies to do so. The script can be run as root, or as a regular user
-# when the PREFIX environment variable is provided.
+# a lot of various dependency packages to work properly. Here's how to build
+# a working mips compiler that can produce code for the R3000A CPU, granted
+# you have the necessary dependencies to do so. The script can be run as
+# root, or as a regular user when the PREFIX environment variable is
+# provided. Set JOBS to override the parallelism, which defaults to the
+# number of available cores.
 #
 
 set -ex
 
 PREFIX=${PREFIX:-"/usr/local"}
+JOBS=${JOBS:-$(nproc 2> /dev/null || echo 1)}
 
 for url in https://ftpmirror.gnu.org/gnu/binutils/binutils-2.47.tar.gz https://mirrors.kernel.org/gnu/binutils/binutils-2.47.tar.gz ; do
     wget --max-redirect=2 --timeout=60 --continue --trust-server-names $url && break
@@ -19,7 +20,7 @@ done
 tar xvfz binutils-2.47.tar.gz
 cd binutils-2.47
 ./configure --target=mipsel-none-elf --disable-multilib --disable-nls --disable-werror --prefix=$PREFIX
-make
+make -j$JOBS
 make install-strip
 cd ..
 
@@ -32,9 +33,9 @@ cd gcc-16.2.0
 mkdir build
 cd build
 ../configure --target=mipsel-none-elf --without-isl --disable-nls --disable-threads --disable-shared --disable-libssp --disable-libstdcxx-pch --disable-libgomp --disable-werror --without-headers --disable-hosted-libstdcxx --with-as=$PREFIX/bin/mipsel-none-elf-as --with-ld=$PREFIX/bin/mipsel-none-elf-ld --enable-languages=c,c++ --prefix=$PREFIX
-make all-gcc
+make -j$JOBS all-gcc
 make install-strip-gcc
-make all-target-libgcc
+make -j$JOBS all-target-libgcc
 make install-strip-target-libgcc
-make all-target-libstdc++-v3
+make -j$JOBS all-target-libstdc++-v3
 make install-strip-target-libstdc++-v3