CI: Add Ubuntu 26.04 builder

The Ubuntu 26.04 LTS, named "Resolute Raccoon, was released on
April 23, 2026.  Add to the supported releases in README.md and
add a CI builder for it.

Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #18547

.github/workflows/scripts/qemu-2-start.sh

@@ -139,6 +139,11 @@ case "$OS" in
     OSv="ubuntu24.04"
     URL="$UBMIRROR/noble/current/noble-server-cloudimg-amd64.img"
     ;;
+  ubuntu26)
+    OSNAME="Ubuntu 26.04"
+    OSv="ubuntu24.04"
+    URL="$UBMIRROR/resolute/current/resolute-server-cloudimg-amd64.img"
+    ;;
   *)
     echo "Wrong value for OS variable!"
     exit 111

.github/workflows/scripts/qemu-3-deps-vm.sh

@@ -215,7 +215,7 @@ case "$1" in
   tumbleweed)
     tumbleweed
     ;;
-  ubuntu*)
+  ubuntu22|ubuntu24)
     debian
     echo "##[group]Install Ubuntu specific"
     sudo apt-get install -yq linux-tools-common libtirpc-dev \
@@ -226,6 +226,27 @@ case "$1" in
     # https://github.com/actions/runner-images/issues/9946
     sudo apt-get install -yq build-essential
 
+    echo "##[endgroup]"
+    echo "##[group]Delete Ubuntu OpenZFS modules"
+    for i in $(find /lib/modules -name zfs -type d); do sudo rm -rvf $i; done
+    echo "##[endgroup]"
+    ;;
+  ubuntu26)
+    debian
+    echo "##[group]Install Ubuntu specific"
+    # Skip linux-modules-extra which is already installed
+    sudo apt-get install -yq linux-tools-common
+    sudo apt-get install -yq libtirpc-dev
+    sudo apt-get install -yq dh-sequence-dkms
+
+    # Need 'build-essential' explicitly for ARM builder
+    # https://github.com/actions/runner-images/issues/9946
+    sudo apt-get install -yq build-essential
+
+    # Replace sudo-rs with sudo for now because the Rust version
+    # does not support -E to preserve the entire environment
+    sudo update-alternatives --set sudo /usr/bin/sudo.ws
+
     echo "##[endgroup]"
     echo "##[group]Delete Ubuntu OpenZFS modules"
     for i in $(find /lib/modules -name zfs -type d); do sudo rm -rvf $i; done
@@ -292,7 +313,7 @@ case "$1" in
     echo 'GRUB_SERIAL_COMMAND="serial --speed=115200"' \
       | sudo tee -a /etc/default/grub >/dev/null
     ;;
-  ubuntu24)
+  ubuntu24|ubuntu26)
     GRUB_CFG="/boot/grub/grub.cfg"
     GRUB_MKCONFIG="grub-mkconfig"
     echo 'GRUB_DISABLE_OS_PROBER="false"' \

.github/workflows/zfs-qemu.yml

@@ -49,17 +49,17 @@ jobs:
             os_selection='[]'
             ;;
           quick)
-            os_selection='["almalinux8", "almalinux9", "almalinux10", "debian12", "fedora44", "freebsd15-1s", "ubuntu24"]'
+            os_selection='["almalinux8", "almalinux9", "almalinux10", "debian12", "fedora44", "freebsd15-1s", "ubuntu26"]'
             ;;
           linux)
-            os_selection='["almalinux8", "almalinux9", "almalinux10", "centos-stream9", "centos-stream10", "debian11", "debian12", "debian13", "fedora43", "fedora44", "ubuntu22", "ubuntu24"]'
+            os_selection='["almalinux8", "almalinux9", "almalinux10", "centos-stream9", "centos-stream10", "debian11", "debian12", "debian13", "fedora43", "fedora44", "ubuntu22", "ubuntu24", "ubuntu26"]'
             ;;
           freebsd)
             os_selection='["freebsd14-4r", "freebsd14-4s", "freebsd15-1s", "freebsd16-0c"]'
             ;;
           *)
             # default list
-            os_selection='["almalinux8", "almalinux9", "almalinux10", "centos-stream9", "centos-stream10", "debian12", "debian13", "fedora43", "fedora44", "freebsd14-4r", "freebsd15-1s", "freebsd16-0c", "ubuntu22", "ubuntu24"]'
+            os_selection='["almalinux8", "almalinux9", "almalinux10", "centos-stream9", "centos-stream10", "debian12", "debian13", "fedora43", "fedora44", "freebsd14-4r", "freebsd15-1s", "freebsd16-0c", "ubuntu22", "ubuntu24", "ubuntu26"]'
             ;;
           esac
 
@@ -99,7 +99,7 @@ jobs:
       fail-fast: false
       matrix:
         # rhl:     almalinux8, almalinux9, centos-streamX, fedora4x
-        # debian:  debian12, debian13, ubuntu22, ubuntu24
+        # debian:  debian12, debian13, ubuntu22, ubuntu24, ubuntu26
         # misc:    archlinux, tumbleweed
         # FreeBSD variants of november 2025:
         # FreeBSD Release: freebsd14-4r, freebsd15-0r

README.md

@@ -52,7 +52,7 @@ All RHEL (and compatible systems: AlmaLinux OS, Rocky Linux, etc) on the **full*
 
 All Ubuntu **LTS** releases are supported.
 
-**Supported Ubuntu releases**: **24.04 “Noble”**, **22.04 “Jammy”**.
+**Supported Ubuntu releases**: **26.04 “Resolute”**, **24.04 “Noble”**, **22.04 “Jammy”**.
 
 ### Debian