[TRY] Mark i686-unknown-linux-gnu as TEST_EVERYTHING setup

Author: sayantn

.github/workflows/main.yml

@@ -141,6 +141,10 @@ jobs:
             tuple: s390x-unknown-linux-gnu
             os: ubuntu-latest
           test_everything: true
+        - target:
+            tuple: i686-unknown-linux-gnu
+            os: ubuntu-latest
+          test_everything: true
         - target:
             tuple: x86_64-unknown-linux-gnu
             os: ubuntu-latest

ci/docker/i686-unknown-linux-gnu/Dockerfile

@@ -4,4 +4,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   libc6-dev \
   file \
   make \
-  ca-certificates
+  ca-certificates \
+  wget \
+  xz-utils
+
+RUN wget http://ci-mirrors.rust-lang.org/stdarch/sde-external-9.53.0-2025-03-16-lin.tar.xz -O sde.tar.xz
+RUN mkdir intel-sde
+RUN tar -xJf sde.tar.xz --strip-components=1 -C intel-sde
+ENV CARGO_TARGET_I686_UNKNOWN_LINUX_GNU_RUNNER="/intel-sde/sde \
+            -cpuid-in /checkout/ci/docker/x86_64-unknown-linux-gnu/cpuid.def \
+            -rtm-mode full -tsx --"
+# These tests fail with SDE as it doesn't support saving register data
+ENV STDARCH_TEST_SKIP_FUNCTION="xsave,xsaveopt,xsave64,xsaveopt64"