Re: [PATCH 3/5] libata: Implement disk shock protection support

From: Robert Hancock
Date: Tue Aug 05 2008 - 00:05:25 EST


Alan Cox wrote:
On Mon, 4 Aug 2008 16:28:32 +0200
Gabor Gombas <gombasg@xxxxxxxxx> wrote:

On Fri, Aug 01, 2008 at 04:19:26PM +0900, Tejun Heo wrote:

However, SATA or not, there simply isn't a way to abort commands in ATA.
Issuing random command while other commands are in progress simply is
state machine violation and there will be many interesting results
including complete system lockup (ATA controller dying while holding the
PCI bus).
A system lockup may be an acceptable compromise if that saves the
hardware. Maybe the kernel should explicitely panic unless the
controller/drive is known to be able to recover.

We've already been told that the accelerometer will now and then randomly
trigger due to other shock patterns like a bump. I don't want my laptop
to panic randomly on train journeys thank you.

Yes, from what I've seen on these laptops, it doesn't take much to trigger the shock protection in Windows - lifting the front of the laptop off the table an inch and dropping it will do it, as will picking it up and suddenly tilting it. (I think the idea is to detect situations where the laptop starts to fall, as by the time it impacts the floor it's too late.) There's an option in the settings to "ignore repetitive shocks as experienced in a train or automobile".

So yes, it's reasonable to expect the shock protection to be triggered pretty often.
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