Force kernel to load rootfs only for legacy SAR devices

app/src/main/java/com/topjohnwu/magisk/core/Info.kt

@@ -28,6 +28,7 @@ object Info {
     // Device state
     @JvmStatic val env by lazy { loadState() }
     @JvmField var isSAR = false
+    var legacySAR = false
     var isAB = false
     @JvmField val isZygiskEnabled = System.getenv("ZYGISK_ENABLED") == "1"
     @JvmStatic val isFDE get() = crypto == "block"

app/src/main/java/com/topjohnwu/magisk/core/tasks/MagiskInstaller.kt

@@ -492,7 +492,7 @@ abstract class MagiskInstallImpl protected constructor(
             "KEEPVERITY=${Config.keepVerity} " +
             "PATCHVBMETAFLAG=${Config.patchVbmeta} " +
             "RECOVERYMODE=${Config.recovery} " +
-            "SYSTEM_ROOT=${Info.isSAR} " +
+            "LEGACYSAR=${Info.legacySAR} " +
             "sh boot_patch.sh $srcBoot")
         val isSuccess = cmds.sh().isSuccess
 

app/src/main/java/com/topjohnwu/magisk/core/utils/ShellInit.kt

@@ -78,6 +78,7 @@ class ShellInit : Shell.Initializer() {
         Info.vbmeta = getBool("VBMETAEXIST")
         Info.isAB = getBool("ISAB")
         Info.crypto = getVar("CRYPTOTYPE")
+        Info.legacySAR = getBool("LEGACYSAR")
 
         // Default presets
         Config.recovery = getBool("RECOVERYMODE")

app/src/main/res/raw/manager.sh

@@ -154,7 +154,7 @@ check_boot_ramdisk() {
   $ISAB && return 0
 
   # If we are using legacy SAR, but not A/B, assume we do not have ramdisk
-  if grep ' / ' /proc/mounts | grep -q '/dev/root'; then
+  if $LEGACYSAR; then
     # Override recovery mode to true
     RECOVERYMODE=true
     return 1
@@ -211,6 +211,11 @@ get_flags() {
   PATCHVBMETAFLAG=false
   # Make sure RECOVERYMODE has value
   [ -z $RECOVERYMODE ] && RECOVERYMODE=false
+  if grep ' / ' /proc/mounts | grep -q '/dev/root'; then
+    LEGACYSAR=true
+  else
+    LEGACYSAR=false
+  fi
 }
 
 run_migrations() { return; }
@@ -223,9 +228,9 @@ grep_prop() { return; }
 
 app_init() {
   mount_partitions
+  get_flags
   RAMDISKEXIST=false
   check_boot_ramdisk && RAMDISKEXIST=true
-  get_flags
   run_migrations
   SHA1=$(grep_prop SHA1 $MAGISKTMP/.magisk/config)
   check_encryption