Date: Tue, 24 Nov 2015 09:04:29 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>, Sreekanth.Reddy@avagotech.com,
        hare@suse.de, martin.petersen@oracle.com, linux-kernel@vger.kernel.org
Subject: Re: MPT2SAS boot fail... due to silently loosing the driver
Message-ID: <20151124080429.GA3398@gmail.com>
References: <20151123124621.GF7520@twins.programming.kicks-ass.net>
 <20151124075149.GB29572@lst.de>
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* Christoph Hellwig <hch@lst.de> wrote:

> I wonder what the "classic" way to such transitions is.  Adding a mpt2 option 
> that just selects mpt3 sound easy, but might be very confusing.

I was hit by the same problem, and wasted some time on it before Peter did his 
time wasting, so a solution would be nice.

An interactive SCSI_MPT2SAS option has to exist in any case, so that we can 
migrate those people who have it configured - and its help text should explain 
that it's a legacy setting that should not be used anymore. That won't be 
confusing.

Then the MPT3 section can do something like:

	# Default to enabled if the config has the old driver enabled:
	default y if SCSI_MPT2SAS

Doing this will also help bisectability: right now we cannot bisect on that system 
without figuring out whether to enable MPT2 or MPT3 at every single bisection 
step.

Don't ever break configs this way. Please!

Also, please pick hardware version invariant names - do we want to go through this 
again when MPT4 is introduced?

Thanks,

	Ingo
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