Re: [git patches] libata hibernation fixes

[Mark Lord]

Rafael J. Wysocki wrote:
> On Tuesday, 4 of November 2008, Linus Torvalds wrote:
> > On Tue, 4 Nov 2008, Jeff Garzik wrote:
> > > This adds code at a late stage (heading towards -rc4), but does
> > > eliminate a particular spin-up overcycling behavior associated with
> > > hibernation.
> > What does this have to do with hibernation? 
> >
> > If it's a hibernation-only issue, then there is something wrong. 
>
> No, it is not.  On some machines it is a power-off issue, on the others it is
> hibernation and power-off issue.
>
> > Also, if it is an issue for normal power-off as well, then I wonder why 
> > this isn't an issue on Windows. Does windows not spin down disks at all?
>
> In fact, AFAICS, it is an issue on Windows as well, at least if
> other-than-HP-preloaded version of Windows is used.
>
> > IOW, I really don't think this is correct. 
> >
> > I _do_ think that correct might be:
> >
> >  - maybe we just do something odd and different, triggering some BIOS 
> >    behavior that isn't there under Windows.
> >
> >    So we should power down thigns differently so that the BIOS.
> >
> >  - quite possibly: we just should not spin down disks at all, and just 
> >    flush them and do the "park" command thing. If we're _really_ powering 
> >    off, the disks will spin down on their own when power goes away. Maybe 
> >    that's what Windows does?
> >
> > So I really don't want to pull this, because I want to get more of an 
> > explanation for why we need to do this at all. I also don't think this is 
> > even appropriate at this stage in -rc.
> >
> > Is it a regression? If so, that just strengthens the questions above - 
> > what did _we_ start doing wrong that this is needed at all? Let's just 
> > stop doing that, not add some idiotic black-list for somethign that _we_ 
> > do wrong.
>
> This is a regression, but from something like 2.6.25 or even earlier.
> I think what happened is we started to power-off disks at one point and these
> BIOS-es just don't like that.
>
> [Note that the issue only appears in _some_ HP boxes, other vendors don't
> seem to be affected at all.]
..

So, what happens if we just don't ever spin them down from the kernel?
Presumably they still spin-down normally (HP or otherwise) when the BIOS
actually cuts the power at the end of all of this?

Just curious..
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