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From: Grant Likely <grant.likely@linaro.org>
Subject: Re: [PATCH v3 04/17] ARM64 / ACPI: Introduce early_param for "acpi"
To: Bjorn Helgaas <bhelgaas@google.com>, Will Deacon <will.deacon@arm.com>
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Date: Wed, 10 Sep 2014 22:58:14 +0100
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On Wed, 10 Sep 2014 07:21:59 -0600, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Wed, Sep 10, 2014 at 7:04 AM, Will Deacon <will.deacon@arm.com> wrote:
> 
> > 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.