add rd.kiwi.oem.maxdisk= boot parameter

this limits the disks considered for oem deployment to a given size

doc/source/overview/workflow.rst

@@ -875,6 +875,16 @@ the available kernel boot parameters for this modules:
   Note that options starting with `rd.kiwi` are not passed on to avoid
   side effects.
 
+``rd.kiwi.oem.maxdisk=size[KMGT]``
+  This variable configures the maximum disk size an unattended oem
+  installation should consider for image deployment. Unattended oem
+  deployments default to deploying on /dev/sda (more exactly, the first
+  device not filtered out by `oem-device-filter`). With RAID
+  controllers, it can happen that your buch of big JBOD disks is for
+  example `/dev/sda` to `/dev/sdi` and the 480G RAID1 configured for
+  OS deployment is `/dev/sdj`. With `rd.kiwi.oem.maxdisk=500G` the
+  deployment will land on that RAID disk.
+
 ``rd.live.overlay.persistent``
   This variable tells a live iso image to prepare a persistent
   write partition.

dracut/modules.d/90kiwi-dump/kiwi-dump-image.sh

@@ -45,10 +45,17 @@ function get_disk_list {
     local disk_device_by_id
     local disk_meta
     local list_items
+    local max_disk
+    local kiwi_oem_maxdisk
     local blk_opts="-p -n -r -o NAME,SIZE,TYPE"
     if [ -n "${kiwi_devicepersistency}" ];then
         disk_id=${kiwi_devicepersistency}
     fi
+    max_disk=0
+    kiwi_oem_maxdisk=$(getarg rd.kiwi.oem.maxdisk=)
+    if [ -n "${kiwi_oem_maxdisk}" ]; then
+        max_disk=$(binsize_to_bytesize "${kiwi_oem_maxdisk}") || max_disk=0
+    fi
     if getargbool 0 rd.kiwi.ramdisk; then
         # target should be a ramdisk on request. Thus actively
         # load the ramdisk block driver and support custom sizes
@@ -77,6 +84,14 @@ function get_disk_list {
             continue
         fi
         disk_size=$(echo "${disk_meta}" | cut -f2 -d:)
+        if [ ${max_disk} -gt 0 ]; then
+            local disk_size_bytes
+            disk_size_bytes=$(binsize_to_bytesize "${disk_size}") || disk_size_bytes=0
+            if [ "${disk_size_bytes}" -gt "${max_disk}" ]; then
+                info "${disk_device} filtered out by rd.kiwi.oem.maxdisk=${kiwi_oem_maxdisk} (is ${disk_size})" >&2
+                continue
+            fi
+        fi
         disk_device_by_id=$(
             get_persistent_device_from_unix_node "${disk_device}" "${disk_id}"
         )

dracut/modules.d/99kiwi-lib/kiwi-lib.sh

@@ -113,3 +113,20 @@ function import_file {
         eval "export ${key}" &>/dev/null
     done < ${source_format}
 }
+
+function binsize_to_bytesize {
+    # """
+    # converts binary sizes (1024k, 2.4G) to bytes
+    # uses awk to handle floating point numbers
+    # """
+    local sz="$1"
+    local bs=${sz:0:-1}
+    case ${sz} in
+        *K|*k) mult=1024 ;;
+        *M) mult=$((1024*1024)) ;;
+        *G) mult=$((1024*1024*1024)) ;;
+        *T) mult=$((1024*1024*1024*1024)) ;;
+        *) bs=${sz}; mult=1 ;;
+    esac
+    awk "BEGIN {print int(${bs}*${mult})}"
+}