[ltp] Re: [Hdaps-devel] Make disk-protect work on 2.6.24 (was: enabling protect file for hdaps on t61)

[alkos333]

Where exactly is this "usual" patch that you are referring to?

On Feb 13, 2008 5:39 AM, Elias Oltmanns <eo@nebensachen.de> wrote:
> [cc'ing hdaps-devel]
>
> Vincent C Jones <v.jones@networkingunlimited.com> wrote:
> > On Mon, 2008-02-11 at 07:58 +0100, Elias Oltmanns wrote:
> >> Vincent C Jones <v.jones@networkingunlimited.com> wrote:
> >> >
> >> > SATA drive here as well (7675 X61, AHCI mode, SuSE 10.3, 2.6.24 with
> >> > SuSE, acpi, protect, & tp_smapi patches applied) and I have no problem
> >> > invoking a freeze. What is your magic incantation to avoid the problem?
> >> > I really would like to get HDAPS back...
> >>
> >> The difference isn't so much SATA vs PATA but SMP system vs uniprocessor
> >> / non-SMP system. Probably Rolf is running an SMP kernel on a dual core
> >> machine whereas your system is lacking SMP support.
> >
> > Huh? SMP -> problem or SMP is OK? SMP kernel with dual core CPU = freeze
>
> Quite right, my analysis was flawed since we seem to have a busy loop
> rather than an infinite recursion. Since some of you don't have the
> freeze problem, I suppose some kernel config options influence the
> scheduler in such a way that I/O either gets a chance or not.
>
> Anyway, there is a temporary solution to this problem. If you apply the
> little patch attached to this email, the usual disk-protect patch will
> work on 2.6.24. This change is supposed to fix a generic problem in
> libata and may eventually be merged upstream, but Tejun Heo (libata
> developer) said that some testing was required first.
>
> This change is absolutely safe for everyone using a non-NCQ capable
> system. In particular, ata_piix doesn't support NCQ. If you are using
> ahci and /sys/class/scsi_disk/.../device/queue_depth reports a value
> greater than 1, i.e. NCQ is enabled, then the patch shouldn't cause any
> harm either but it may or may not affect I/O performance.
>
> Enjoy,
>
> Elias
>
>
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