diff --git a/build/meta-bsp/classes/bsp.bbclass b/build/meta-bsp/classes/bsp.bbclass
index 8b7c57a51..0e5638bef 100644
--- a/build/meta-bsp/classes/bsp.bbclass
+++ b/build/meta-bsp/classes/bsp.bbclass
@@ -166,7 +166,10 @@ inherit filesystem
 # `deploy.sh <bsp>` without a prior build still pulls them through sstate).
 
 do_deploy_boot_chain[nostamp] = "1"
-do_deploy_boot_chain[depends] = "uboot:do_build"
+# filesystem:do_fs_check because a chain may write its first stage into the
+# raw area of the card (bsp_virt64.inc, IB_FIRST_STAGE_FROM_CARD): on a fresh
+# tree the storage image must exist before, not be created by do_deploy after.
+do_deploy_boot_chain[depends] = "uboot:do_build filesystem:do_fs_check"
 
 python () {
     extra = []
diff --git a/build/meta-filesystem/classes/fs_arm_common.bbclass b/build/meta-filesystem/classes/fs_arm_common.bbclass
index 30ddea85c..ff2eb7c24 100644
--- a/build/meta-filesystem/classes/fs_arm_common.bbclass
+++ b/build/meta-filesystem/classes/fs_arm_common.bbclass
@@ -27,6 +27,7 @@ IB_PARTITION_LAYOUT ?= "${@'ab' if d.getVar('IB_ZEPHYR_BOOT_APP') else 'rootfs'}
 def __platform_init_storage(d):
     import os
     import subprocess
+    import time
 
     IB_STORAGE_MODE = d.getVar('IB_STORAGE_MODE')
     IB_ROOTFS_SIZE = d.getVar('IB_ROOTFS_SIZE')
@@ -128,14 +129,26 @@ def __platform_init_storage(d):
 
     print("Waiting ...")
 
-    # TODO: use ionotify(7)
-    # Give a chance to the real SD-card to be sync'd
-    time.sleep(2)
-
     if devname[-1].isdigit():
         devname += "p"
 
-    utils_sudo(["mkfs.fat", "-F32", "-a", "-v", "-n", "boot", f"/dev/{devname}1"])
+    # Wait for the partition nodes rather than a fixed delay. They are created
+    # asynchronously by the host's udev, and inside the build container
+    # (dbuild.sh bind-mounts the host /dev) that regularly takes longer than
+    # the 2 s this used to sleep: mkfs then ran on a node that did not exist
+    # yet, failed, and the card was left with an unformatted p1 that only
+    # showed up as a failed mount in the next deploy.
+    parts = ("1", "2", "3") if layout == "ab" else ("1", "2")
+    for _ in range(100):
+        if all(os.path.exists(f"/dev/{devname}{n}") for n in parts):
+            break
+        time.sleep(0.2)
+    else:
+        bb.fatal(f"/dev/{devname}{{{','.join(parts)}}} did not appear after "
+                 "partitioning /dev/" + devname.rstrip("p"))
+
+    utils_sudo(["mkfs.fat", "-F32", "-a", "-v", "-n", "boot", f"/dev/{devname}1"],
+               check=True)
 
     if layout == "ab":
         # p2 and p3 are raw slots. A filesystem on them would be a filesystem
@@ -146,7 +159,7 @@ def __platform_init_storage(d):
             utils_sudo(["dd", "if=/dev/zero", f"of=/dev/{devname}{part}",
                         "bs=1M", "count=1", "conv=fsync"])
     else:
-        utils_sudo(["mkfs.ext4", "-L", "rootfs1", f"/dev/{devname}2"])
+        utils_sudo(["mkfs.ext4", "-L", "rootfs1", f"/dev/{devname}2"], check=True)
 
     if IB_STORAGE_MODE == "soft":
         utils_sudo(["losetup", "-D"])
diff --git a/build/meta-usr/recipes-usr/linux/usr-linux_1.0.bb b/build/meta-usr/recipes-usr/linux/usr-linux_1.0.bb
index dfbede236..77a39b530 100644
--- a/build/meta-usr/recipes-usr/linux/usr-linux_1.0.bb
+++ b/build/meta-usr/recipes-usr/linux/usr-linux_1.0.bb
@@ -74,8 +74,20 @@ python do_deploy() {
 
         d.setVar('ROOTFS_FILENAME', 'rootfs')
         __do_rootfs_mount(d)
-        utils_sudo(["rsync", "-a", "--keep-dirlinks",
-                    deploy_src + "/", f"{IB_ROOTFS_PATH}/fs/"], check=True)
+
+        # A failed copy must not leave the extracted, root-owned tree behind,
+        # as the p2 path below makes sure of for its mount. But not through a
+        # plain finally: __do_rootfs_umount re-packs the tree INTO rootfs.cpio,
+        # and a half-copied user space must not end up there. On failure the
+        # tree is dropped and rootfs.cpio stays as it was; the next deploy
+        # starts over from it.
+        try:
+            utils_sudo(["rsync", "-a", "--keep-dirlinks",
+                        deploy_src + "/", f"{IB_ROOTFS_PATH}/fs/"], check=True)
+        except Exception:
+            utils_sudo(["rm", "-rf", os.path.join(d.getVar('WORKDIR'), "fs")])
+            raise
+
         __do_rootfs_umount(d)
 
         bb.plain("usr deployed into rootfs.cpio (IB_RAMFS_SOURCE = rootfs)")
@@ -146,10 +158,14 @@ do_install_apps () {
     usr_do_install_file_root "${IB_TARGET}/src/modules/*.ko"
 }
 
-do_clean:append () {
+# usr.bbclass defines do_clean in Python, and a shell :append is pasted
+# verbatim into that Python function, so `-c clean` died on a SyntaxError.
+# The shell stays shell, in its own function, called from a Python append.
+usr_linux_clean () {
     
-    # Clean the modules
-    if [ -d ${IB_TARGET}/src/modules ]; then
+    # Clean the modules — only when there is a kernel tree to clean them
+    # against; before the first linux build there is nothing to clean.
+    if [ -d ${IB_TARGET}/src/modules ] && [ -d ${IB_LINUX_PATH} ]; then
 	    make -C ${IB_LINUX_PATH} M=${IB_TARGET}/src/modules clean
     fi
     
@@ -166,3 +182,7 @@ do_clean:append () {
    # Clean the user space apps
    rm -rf ${IB_TARGET}/build
 }
+
+python do_clean:append () {
+    bb.build.exec_func('usr_linux_clean', d)
+}
diff --git a/build/meta-usr/recipes-usr/lvgl/usr-linux_1.0.bbappend b/build/meta-usr/recipes-usr/lvgl/usr-linux_1.0.bbappend
index fc61b713f..f518015c1 100644
--- a/build/meta-usr/recipes-usr/lvgl/usr-linux_1.0.bbappend
+++ b/build/meta-usr/recipes-usr/lvgl/usr-linux_1.0.bbappend
@@ -60,7 +60,10 @@ do_install_apps:append () {
     fi
 }
 
-do_clean:append () {
+# usr.bbclass defines do_clean in Python, and a shell :append is pasted
+# verbatim into that Python function, so `-c clean` died on a SyntaxError.
+# The shell stays shell, in its own function, called from a Python append.
+usr_linux_clean_lvgl () {
    
     if echo ":${OVERRIDES}:" | grep -q ":lvgl"; then
       
@@ -76,3 +79,7 @@ do_clean:append () {
         rm -rf ${WORKDIR}/git
     fi
 }
+
+python do_clean:append () {
+    bb.build.exec_func('usr_linux_clean_lvgl', d)
+}
diff --git a/scripts/dbuild.sh b/scripts/dbuild.sh
index 1c4292ff3..29f58cc30 100755
--- a/scripts/dbuild.sh
+++ b/scripts/dbuild.sh
@@ -119,6 +119,16 @@ fi
 
 set -- -e IB_TREE="$IB_ROOT" -e IB_CWD="$cwd" "$@"
 
+# Forward the per-invocation knobs env.sh lets through to bitbake
+# (BB_ENV_PASSTHROUGH_ADDITIONS) when they are set on the host. Without it
+# `IB_FORCE_ATTACH=1 dbuild.sh build.sh <recipe>` — what the attach guard
+# itself advises — never reached the container, and the guard kept refusing.
+
+for _v in IB_FORCE_ATTACH IB_PARTITION_LAYOUT; do
+	eval "_val=\${$_v:-}"
+	[ -n "$_val" ] && set -- -e "$_v=$_val" "$@"
+done
+
 # Hardware deployment: make any IB_HTTP_DEPLOY_PATH feed directory
 # visible at its own path so `deploy.sh` can publish into it from inside
 # (IB_STORAGE_MODE=http). This serves the verdin-imx8mp TEZI flow; on the