adb root command works in development builds only (i.e.
userdebug which have
ro.debuggable=1 by default). So to enable the
adb root command on your otherwise rooted device just add the
ro.debuggable=1 line to one of the following files:
/system/build.prop /system/default.prop /data/local.prop
If you want
adb shell to start as
root by default – then add
ro.secure=0 as well.
Alternatively you could use modified
adbd binary (which does not check for
#if defined(ALLOW_ADBD_ROOT) // The properties that affect `adb root` and `adb unroot` are ro.secure and // ro.debuggable. In this context the names don't make the expected behavior // particularly obvious. // // ro.debuggable: // Allowed to become root, but not necessarily the default. Set to 1 on // eng and userdebug builds. // // ro.secure: // Drop privileges by default. Set to 1 on userdebug and user builds.