Good news for all owners of the Lenovo IdeaPad Y470 and Lenovo IdeaPad Y570, A temporary solution has been worked out that by-passes the detection issue in the kernel:
https://bugzilla.kernel.org/show_bug.cgi?id=42696
Until a correct fix is committed to the upstream kernel, you can use this solution for overwriting the wrongly detected ACPI handle. More information here:
https://github.com/Bumblebee-Project/bbswitch/issues/2#issuecomment-3797568
Please note that this is just a temporary solution.
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