On Wed, 10 Sep 2014 07:21:59 -0600, Bjorn Helgaas [off-list ref] wrote:

On Wed, Sep 10, 2014 at 7:04 AM, Will Deacon [off-list ref] wrote:

quoted

It's blindingly obvious that acpi=off is there to disable ACPI at boot.
We either support that option or we don't -- none of this `oh, well you
can use it in this specific case I suppose' rubbish. I'm not questioning
your use-case, but there's really no need to talk about an `orderly
adoption' when all you need to say is that your ACPI is busted and passing
acpi=off lets you boot with a devicetree.

Maybe we should set a taint bit or give some other indication that
we're using a flag to work around breakage.

Nope. No taint. Maybe a log message, but there are perfectly valid
reasons to use acpi=off, such as the user has a DT for the hardware
that moves all the PM operations into the kernel-proper to tune for a
very specific use case. This moves outside the support envelope, but
that doesn't make it a bad thing or the wrong thing to do.

g.