Remove support for Linux x86 builds (#626)

We stopped shipping the distributions in
6fa8fe9 in October 2023. At the time we
preserved build support just in case.

I don't believe anyone has complained about the loss of x86 Linux
distributions.

I don't believe there is compelling value in PBS supporting x86 Linux
distributions.

If someone wants to run Python on x86 Linux, they can always use
CPython's official build systen, which still supports targeting x86
Linux.

This commit rips out our support building for x86 Linux.

Author: indygreg

cpython-unix/base.Dockerfile

@@ -29,10 +29,6 @@ RUN for s in debian_jessie debian_jessie-updates debian-security_jessie/updates;
       echo 'Acquire::Retries "5";'; \
     ) > /etc/apt/apt.conf.d/99cpython-portable
 
-RUN ( echo 'amd64'; \
-      echo 'i386'; \
-    ) > /var/lib/dpkg/arch
-
 # apt iterates all available file descriptors up to rlim_max and calls
 # fcntl(fd, F_SETFD, FD_CLOEXEC). This can result in millions of system calls
 # (we've seen 1B in the wild) and cause operations to take seconds to minutes.

cpython-unix/build-cpython.sh

@@ -91,6 +91,9 @@ fi
 
 # Configure nerfs RUNSHARED when cross-compiling, which prevents PGO from running when
 # we can in fact run the target binaries (e.g. x86_64 host and i686 target). Undo that.
+# TODO this may not be needed after removing support for i686 builds. But it
+# may still be useful since CPython's definition of cross-compiling has historically
+# been very liberal and kicks in when it arguably shouldn't.
 if [ -n "${CROSS_COMPILING}" ]; then
     if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_14}" ]; then
         patch -p1 -i ${ROOT}/patch-dont-clear-runshared-14.patch
@@ -1058,9 +1061,6 @@ armv7-unknown-linux-gnueabi)
 armv7-unknown-linux-gnueabihf)
     PYTHON_ARCH="arm-linux-gnueabihf"
     ;;
-i686-unknown-linux-gnu)
-    PYTHON_ARCH="i386-linux-gnu"
-    ;;
 mips-unknown-linux-gnu)
     PYTHON_ARCH="mips-linux-gnu"
     ;;

cpython-unix/build-libX11.sh

@@ -54,9 +54,6 @@ if [ -n "${CROSS_COMPILING}" ]; then
     armv7-unknown-linux-gnueabihf)
       EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
       ;;
-    i686-unknown-linux-gnu)
-      EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
-      ;;
     mips-unknown-linux-gnu)
       EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
       ;;
@@ -81,9 +78,6 @@ if [ -n "${CROSS_COMPILING}" ]; then
     aarch64-unknown-linux-musl)
       EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
       ;;
-    i686-unknown-linux-musl)
-      EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
-      ;;
     mips-unknown-linux-musl)
       EXTRA_FLAGS="${EXTRA_FLAGS} --enable-malloc0returnsnull"
       ;;

cpython-unix/build.Dockerfile

@@ -1,8 +1,5 @@
 {% include 'base.Dockerfile' %}
 
-# libc6-dev:i386 pulls in 32-bit system libraries to enable cross-compiling
-# to i386.
-#
 # libffi-dev and zlib1g-dev are present so host Python (during cross-builds)
 # can build the ctypes and zlib extensions. So comment in build-cpython.sh
 # for more context.
@@ -14,7 +11,6 @@ RUN ulimit -n 10000 && apt-get install \
     bzip2 \
     file \
     libc6-dev \
-    libc6-dev:i386 \
     libffi-dev \
     make \
     patch \

cpython-unix/extension-modules.yml

@@ -249,7 +249,6 @@ _decimal:
     - define: CONFIG_32=1
       targets:
         - armv7-.*
-        - i686-.*
         - mips-.*
         - mipsel-.*
     - define: CONFIG_64=1
@@ -299,7 +298,6 @@ _hashlib:
     # a static library so there isn't a runtime dependency.
     - name: ':libatomic.a'
       targets:
-        - i686-unknown-linux-gnu
         - mips-unknown-linux-gnu
         - mipsel-unknown-linux-gnu
         - x86_64.*-unknown-linux-gnu
@@ -570,7 +568,6 @@ _ssl:
     # a static library so there isn't a runtime dependency.
     - name: ':libatomic.a'
       targets:
-        - i686-unknown-linux-gnu
         - mips-unknown-linux-gnu
         - mipsel-unknown-linux-gnu
         - x86_64.*-unknown-linux-gnu

cpython-unix/targets.yml

@@ -318,52 +318,6 @@ armv7-unknown-linux-gnueabihf:
     - zlib
   openssl_target: linux-armv4
 
-i686-unknown-linux-gnu:
-  host_platforms:
-    - linux_x86_64
-  pythons_supported:
-    - '3.9'
-    - '3.10'
-    - '3.11'
-    - '3.12'
-    - '3.13'
-    - '3.14'
-  needs_toolchain: true
-  host_cc: clang
-  host_cxx: clang++
-  target_cc: clang
-  target_cxx: clang++
-  target_cflags:
-    - '-m32'
-    - '-fvisibility=hidden'
-  target_ldflags:
-    - '-m32'
-  needs:
-    - autoconf
-    - bdb
-    - binutils
-    - bzip2
-    - expat
-    - libedit
-    - libffi
-    - libX11
-    - libXau
-    - libxcb
-    - m4
-    - mpdecimal
-    - ncurses
-    - openssl-3.0
-    - patchelf
-    - sqlite
-    - tcl
-    - tk
-    - tix
-    - uuid
-    - xorgproto
-    - xz
-    - zlib
-  openssl_target: linux-x86-clang
-
 mips-unknown-linux-gnu:
   host_platforms:
     - linux_x86_64