install: Enable installing to multi device parents

crates/lib/src/bootc_composefs/boot.rs

@@ -520,8 +520,23 @@ pub(crate) fn setup_composefs_bls_boot(
 
             cmdline_options.extend(&Cmdline::from(&composefs_cmdline));
 
-            // Locate ESP partition device
-            let esp_part = esp_in(&root_setup.device_info)?;
+            // Find all ESP partitions across all backing devices.
+            // For composefs with systemd-boot, we only support a single ESP.
+            let mut esp_parts: Vec<&bootc_blockdev::Partition> = Vec::new();
+            for device in &root_setup.device_info {
+                if let Some(esp) = device.find_partition_of_esp()? {
+                    esp_parts.push(esp);
+                }
+            }
+            let esp_part = match esp_parts.len() {
+                0 => {
+                    anyhow::bail!("Cannot locate ESP: no ESP partition found on any backing device")
+                }
+                1 => esp_parts.into_iter().next().unwrap(),
+                n => anyhow::bail!(
+                    "Found {n} ESP partitions across backing devices; only a single ESP is supported for composefs boot"
+                ),
+            };
 
             (
                 root_setup.physical_root_path.clone(),
@@ -1063,7 +1078,12 @@ pub(crate) fn setup_composefs_uki_boot(
         BootSetupType::Setup((root_setup, state, postfetch, ..)) => {
             state.require_no_kargs_for_uki()?;
 
-            let esp_part = esp_in(&root_setup.device_info)?;
+            //TODO: Handle multiple devices (RAID, LVM, etc)
+            let device_info = root_setup
+                .device_info
+                .first()
+                .ok_or_else(|| anyhow!("Cannot locate ESP: no backing device found"))?;
+            let esp_part = esp_in(device_info)?;
 
             (
                 root_setup.physical_root_path.clone(),
@@ -1233,7 +1253,8 @@ pub(crate) async fn setup_composefs_boot(
 
     if cfg!(target_arch = "s390x") {
         // TODO: Integrate s390x support into install_via_bootupd
-        crate::bootloader::install_via_zipl(&root_setup.device_info, boot_uuid)?;
+        // zipl only supports single device
+        crate::bootloader::install_via_zipl(root_setup.device_info.first(), boot_uuid)?;
     } else if postfetch.detected_bootloader == Bootloader::Grub {
         crate::bootloader::install_via_bootupd(
             &root_setup.device_info,
@@ -1242,8 +1263,9 @@ pub(crate) async fn setup_composefs_boot(
             None,
         )?;
     } else {
+        // systemd-boot only supports a single ESP
         crate::bootloader::install_systemd_boot(
-            &root_setup.device_info,
+            root_setup.device_info.first(),
             &root_setup.physical_root_path,
             &state.config_opts,
             None,

crates/lib/src/bootloader.rs

@@ -82,7 +82,7 @@ pub(crate) fn supports_bootupd(root: &Dir) -> Result<bool> {
 
 #[context("Installing bootloader")]
 pub(crate) fn install_via_bootupd(
-    device: &PartitionTable,
+    devices: &[PartitionTable],
     rootfs: &Utf8Path,
     configopts: &crate::install::InstallConfigOpts,
     deployment_path: Option<&str>,
@@ -97,26 +97,61 @@ pub(crate) fn install_via_bootupd(
     } else {
         vec![]
     };
-    let devpath = device.path();
-    println!("Installing bootloader via bootupd");
-    Command::new("bootupctl")
-        .args(["backend", "install", "--write-uuid"])
-        .args(verbose)
-        .args(bootupd_opts.iter().copied().flatten())
-        .args(src_root_arg)
-        .args(["--device", devpath.as_str(), rootfs.as_str()])
-        .log_debug()
-        .run_inherited_with_cmd_context()
+
+    // No backing devices with ESP found. Run bootupd without --device and let it
+    // try to auto-detect. This works for:
+    // - BIOS boot (uses MBR, not ESP)
+    // - Systems where bootupd can find ESP via mounted /boot/efi
+    // UEFI boot will fail if bootupd cannot locate the ESP.
+    if devices.is_empty() {
+        tracing::warn!(
+            "No backing device with ESP found; UEFI boot may fail if ESP cannot be auto-detected"
+        );
+        println!("Installing bootloader via bootupd (no target device specified)");
+        return Command::new("bootupctl")
+            .args(["backend", "install", "--write-uuid"])
+            .args(verbose)
+            .args(bootupd_opts.iter().copied().flatten())
+            .args(&src_root_arg)
+            .arg(rootfs.as_str())
+            .log_debug()
+            .run_inherited_with_cmd_context();
+    }
+
+    // Install bootloader to each device
+    for dev in devices {
+        let devpath = dev.path();
+        println!("Installing bootloader via bootupd to {devpath}");
+        Command::new("bootupctl")
+            .args(["backend", "install", "--write-uuid"])
+            .args(verbose)
+            .args(bootupd_opts.iter().copied().flatten())
+            .args(&src_root_arg)
+            .args(["--device", devpath.as_str()])
+            .arg(rootfs.as_str())
+            .log_debug()
+            .run_inherited_with_cmd_context()?;
+    }
+
+    Ok(())
 }
 
 #[context("Installing bootloader")]
 pub(crate) fn install_systemd_boot(
-    device: &PartitionTable,
+    device: Option<&PartitionTable>,
     _rootfs: &Utf8Path,
     _configopts: &crate::install::InstallConfigOpts,
     _deployment_path: Option<&str>,
     autoenroll: Option<SecurebootKeys>,
 ) -> Result<()> {
+    // systemd-boot requires the backing device to locate the ESP partition
+    let device = device.ok_or_else(|| {
+        anyhow!(
+            "Cannot install systemd-boot: no single backing device found \
+             (root may span multiple devices such as LVM across multiple disks)"
+        )
+    })?;
+
     let esp_part = device
         .find_partition_of_type(discoverable_partition_specification::ESP)
         .ok_or_else(|| anyhow::anyhow!("ESP partition not found"))?;
@@ -161,7 +196,15 @@ pub(crate) fn install_systemd_boot(
 }
 
 #[context("Installing bootloader using zipl")]
-pub(crate) fn install_via_zipl(device: &PartitionTable, boot_uuid: &str) -> Result<()> {
+pub(crate) fn install_via_zipl(device: Option<&PartitionTable>, boot_uuid: &str) -> Result<()> {
+    // zipl requires the backing device information to install the bootloader
+    let device = device.ok_or_else(|| {
+        anyhow!(
+            "Cannot install zipl bootloader: no single backing device found \
+             (root may span multiple devices such as LVM across multiple disks)"
+        )
+    })?;
+
     // Identify the target boot partition from UUID
     let fs = mount::inspect_filesystem_by_uuid(boot_uuid)?;
     let boot_dir = Utf8Path::new(&fs.target);

crates/lib/src/install.rs

@@ -1141,7 +1141,10 @@ pub(crate) fn exec_in_host_mountns(args: &[std::ffi::OsString]) -> Result<()> {
 pub(crate) struct RootSetup {
     #[cfg(feature = "install-to-disk")]
     luks_device: Option<String>,
-    pub(crate) device_info: bootc_blockdev::PartitionTable,
+    /// Information about the backing block device partition tables.
+    /// Contains all devices that have an ESP partition when the root filesystem
+    /// spans multiple backing devices (e.g., LVM across multiple disks).
+    pub(crate) device_info: Vec<bootc_blockdev::PartitionTable>,
     /// Absolute path to the location where we've mounted the physical
     /// root filesystem for the system we're installing.
     pub(crate) physical_root_path: Utf8PathBuf,
@@ -1602,7 +1605,9 @@ async fn install_with_sysroot(
 
     if cfg!(target_arch = "s390x") {
         // TODO: Integrate s390x support into install_via_bootupd
-        crate::bootloader::install_via_zipl(&rootfs.device_info, boot_uuid)?;
+        // zipl only supports single device
+        let device = rootfs.device_info.first();
+        crate::bootloader::install_via_zipl(device, boot_uuid)?;
     } else {
         match postfetch.detected_bootloader {
             Bootloader::Grub => {
@@ -1733,15 +1738,21 @@ async fn install_to_filesystem_impl(
     // Drop exclusive ownership since we're done with mutation
     let rootfs = &*rootfs;
 
-    match &rootfs.device_info.label {
-        bootc_blockdev::PartitionType::Dos => crate::utils::medium_visibility_warning(
-            "Installing to `dos` format partitions is not recommended",
-        ),
-        bootc_blockdev::PartitionType::Gpt => {
-            // The only thing we should be using in general
-        }
-        bootc_blockdev::PartitionType::Unknown(o) => {
-            crate::utils::medium_visibility_warning(&format!("Unknown partition label {o}"))
+    // Check partition type of all backing devices
+    for device_info in &rootfs.device_info {
+        match &device_info.label {
+            bootc_blockdev::PartitionType::Dos => {
+                crate::utils::medium_visibility_warning(&format!(
+                    "Installing to `dos` format partitions is not recommended: {}",
+                    device_info.path()
+                ))
+            }
+            bootc_blockdev::PartitionType::Gpt => {
+                // The only thing we should be using in general
+            }
+            bootc_blockdev::PartitionType::Unknown(o) => crate::utils::medium_visibility_warning(
+                &format!("Unknown partition label {o}: {}", device_info.path()),
+            ),
         }
     }
 
@@ -2291,27 +2302,77 @@ pub(crate) async fn install_to_filesystem(
     };
     tracing::debug!("boot UUID: {boot_uuid:?}");
 
-    // Find the real underlying backing device for the root.  This is currently just required
-    // for GRUB (BIOS) and in the future zipl (I think).
-    let backing_device = {
+    // Walk up the block device hierarchy to find physical backing device(s).
+    // Examples:
+    //   /dev/sda3 -> /dev/sda (single disk)
+    //   /dev/mapper/vg-lv -> /dev/sda2, /dev/sdb2 (LVM across two disks)
+    let backing_devices: Vec<String> = {
         let mut dev = inspect.source;
         loop {
             tracing::debug!("Finding parents for {dev}");
-            let mut parents = bootc_blockdev::find_parent_devices(&dev)?.into_iter();
-            let Some(parent) = parents.next() else {
-                break;
-            };
-            if let Some(next) = parents.next() {
-                anyhow::bail!(
-                    "Found multiple parent devices {parent} and {next}; not currently supported"
+            let parents = bootc_blockdev::find_parent_devices(&dev)?;
+            if parents.is_empty() {
+                // Reached a physical disk
+                break vec![dev];
+            }
+            if parents.len() > 1 {
+                // Multi-device (e.g., LVM across disks) - return all
+                tracing::debug!(
+                    "Found multiple parent devices: {:?}; will search for ESP",
+                    parents
                 );
+                break parents;
+            }
+            // Single parent (e.g. LVM LV -> VG -> PV) - keep walking up
+            dev = parents.into_iter().next().unwrap();
+        }
+    };
+    tracing::debug!("Backing devices: {backing_devices:?}");
+
+    // Determine the device and partition info to use for bootloader installation.
+    // If there are multiple backing devices, we search for all that contain an ESP.
+    let device_info: Vec<bootc_blockdev::PartitionTable> = if backing_devices.len() == 1 {
+        // Single backing device - use it directly
+        let dev = &backing_devices[0];
+        vec![bootc_blockdev::partitions_of(Utf8Path::new(dev))?]
+    } else {
+        // Multiple backing devices - find all with ESP
+        let mut esp_devices = Vec::new();
+        for dev in &backing_devices {
+            match bootc_blockdev::partitions_of(Utf8Path::new(dev)) {
+                Ok(table) => {
+                    match table.find_partition_of_esp() {
+                        Ok(Some(_)) => {
+                            tracing::info!("Found ESP on device {dev}");
+                            esp_devices.push(table);
+                        }
+                        Ok(None) => (),
+                        Err(e) => {
+                            // Some partition table types may not be supported for ESP detection.
+                            // Log and continue checking other devices.
+                            tracing::debug!("Could not check for ESP on {dev}: {e}");
+                        }
+                    }
+                }
+                Err(e) => {
+                    // Some backing devices may not have partition tables (e.g., raw LVM PVs
+                    // or whole-disk filesystems). These can't have an ESP, so skip them.
+                    tracing::debug!("Failed to read partition table from {dev}: {e}");
+                }
             }
-            dev = parent;
         }
-        dev
+        if esp_devices.is_empty() {
+            // No ESP found on any backing device. This is not fatal because:
+            // - BIOS boot uses MBR, not ESP
+            // - bootupd may auto-detect ESP via mounted /boot/efi
+            // However, UEFI boot without a detectable ESP will fail.
+            tracing::warn!(
+                "No ESP found on any backing device ({:?}); UEFI boot may fail",
+                backing_devices
+            );
+        }
+        esp_devices
     };
-    tracing::debug!("Backing device: {backing_device}");
-    let device_info = bootc_blockdev::partitions_of(Utf8Path::new(&backing_device))?;
 
     let rootarg = format!("root={}", root_info.mount_spec);
     let mut boot = if let Some(spec) = fsopts.boot_mount_spec {

crates/lib/src/install/baseline.rs

@@ -485,7 +485,7 @@ pub(crate) fn install_create_rootfs(
         BlockSetup::Direct => None,
         BlockSetup::Tpm2Luks => Some(luks_name.to_string()),
     };
-    let device_info = bootc_blockdev::partitions_of(&devpath)?;
+    let device_info = vec![bootc_blockdev::partitions_of(&devpath)?];
     Ok(RootSetup {
         luks_device,
         device_info,

tmt/plans/integration.fmf

@@ -166,4 +166,10 @@ execute:
     how: fmf
     test:
       - /tmt/tests/tests/test-33-bib-build
+/plan-34-multi-device-esp:
+  summary: Test multi-device ESP detection for to-existing-root
+  discover:
+    how: fmf
+    test:
+      - /tmt/tests/test-32-multi-device-esp
 # END GENERATED PLANS