ci: upgrade Ubuntu Docker image to 26.04

ci/docker/aarch64-linux-android/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN dpkg --add-architecture i386
 RUN apt-get update && apt-get install -y --no-install-recommends \

ci/docker/aarch64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/aarch64-unknown-linux-musl/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/arm-linux-androideabi/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN dpkg --add-architecture i386
 RUN apt-get update && apt-get install -y --no-install-recommends \

ci/docker/asmjs-unknown-emscripten/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 # This is a workaround to avoid the interaction with tzdata.
 ENV DEBIAN_FRONTEND=noninteractive

ci/docker/i686-linux-android/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN dpkg --add-architecture i386
 RUN apt-get update && apt-get install -y --no-install-recommends \

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

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
         ca-certificates \

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

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN dpkg --add-architecture i386 && \
     apt-get update && apt-get install -y --no-install-recommends \

ci/docker/loongarch64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/loongarch64-unknown-linux-musl/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/powerpc64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/powerpc64le-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/powerpc64le-unknown-linux-musl/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/riscv64gc-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/s390x-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/s390x-unknown-linux-musl/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     curl \

ci/docker/sparc64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/wasm32-unknown-emscripten/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 # This is a workaround to avoid the interaction with tzdata.
 ENV DEBIAN_FRONTEND=noninteractive

ci/docker/wasm32-wasip1/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 COPY wasi.sh /
 RUN /wasi.sh

ci/docker/wasm32-wasip2/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 COPY wasi.sh /
 RUN /wasi.sh

ci/docker/x86_64-linux-android/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/x86_64-unknown-linux-gnu/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/x86_64-unknown-linux-gnux32/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

ci/docker/x86_64-unknown-linux-musl/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:25.04
+FROM ubuntu:26.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \

libc-test/build.rs

@@ -4164,8 +4164,8 @@ fn test_linux(target: &str) {
             // FIXME(linux): Requires >= 6.12 kernel headers.
             "mnt_ns_info" => true,
 
-            // FIXME(musl): Struct has changed for new musl versions
-            "tcp_info" if musl => true,
+            // FIXME(linux): Struct has changed in newer headers.
+            "tcp_info" if gnu || musl => true,
 
             // FIXME(musl): Supported in new musl but we don't have a new enough version in CI.
             "statx" | "statx_timestamp" if musl => true,
@@ -4338,6 +4338,15 @@ fn test_linux(target: &str) {
             // Users should use SIGSYS instead.
             "SIGUNUSED" => true,
 
+            // FIXME(linux): Deprecated sysctl constants removed from newer kernel headers.
+            "KERN_REALROOTDEV" | "VM_LAPTOP_MODE" => true,
+
+            // FIXME(linux): Values changed in newer kernel headers.
+            "SW_MAX" | "SW_CNT" => true,
+
+            // FIXME(linux): glibc exposes this without sign-extension in newer headers.
+            "MS_NOUSER" if gnu => true,
+
             // FIXME(linux): conflicts with glibc headers and is tested in
             // `linux_termios.rs` below:
             "BOTHER" | "IBSHIFT" | "TCGETS2" | "TCSETS2" | "TCSETSW2" | "TCSETSF2" => true,