Handle partition loading time

lib/modules/partition/disks.nix

@@ -137,6 +137,7 @@
                   create = lib.strings.concatLines [
                     (appendScript "${toString index}: \"$(${sizeOption})\" type=${mkType type}")
                     # Wait for partition to be detected
+                    ''echo "Waiting for ${partVar} to appear..."''
                     ''
                       while true;
                       do
@@ -326,14 +327,23 @@
               partitions = (builtins.concatMap (_: (builtins.attrValues _.partitions)) disks);
 
               mountScript = lib.strings.concatLines (
-                builtins.map
-                  (_: builtins.concatStringsSep " " [
-                    "sudo"
-                    "mount"
-                    "--mkdir"
-                    (builtins.concatStringsSep " " (builtins.map (_: "-o ${_}") _.mountOptions))
-                    (partPath _)
-                    (normalizePath "/${rootDir}/${_.mountPoint}")
+                builtins.concatMap
+                  (_: [
+                  ''echo "Waiting for "${lib.strings.escapeShellArg (partPath _)}" to appear..."''
+                  ''
+                    while true;
+                    do
+                      [ -b ${lib.strings.escapeShellArg (partPath _)} ] && break
+                    done
+                  ''
+                    (builtins.concatStringsSep " " [
+                      "sudo"
+                      "mount"
+                      "--mkdir"
+                      (builtins.concatStringsSep " " (builtins.map (_: "-o ${_}") _.mountOptions))
+                      (partPath _)
+                      (normalizePath "/${rootDir}/${_.mountPoint}")
+                    ])
                   ])
                   (lib.lists.sortOn
                     (_: normalizePath "/${_.mountPoint}")