Doesn't apply to today Linus' git tree:
[fcomolli@tycho linux-2.6]$ git pull git://htj.dyndns.org/libata-tj spindown
remote: Generating pack...
remote: Done counting 14283 objects.
remote: Result has 11254 objects.
remote: Deltifying 11254 objects.
remote: 100% (11254/11254) done
Indexing 11254 objects.
remote: Total 11254 (delta 9842), reused 11241 (delta 9832)
100% (11254/11254) done
Resolving 9842 deltas.
100% (9842/9842) done
1948 objects were added to complete this thin pack.
100% (44114/44114) done
Auto-merged Documentation/feature-removal-schedule.txt
CONFLICT (content): Merge conflict in Documentation/feature-removal-schedule.txt
Automatic merge failed; fix conflicts and then commit the result.
I don't know git enough to identify the conflict. Can anyone help me?
Thanks in advance.
Fabio
On 5/4/07, Tejun Heo <htejun@xxxxxxxxx> wrote:
Hello,
This is another take at using sdev->manage_start_stop to reimplement
suspend/resume and fix spindown on poweroff. As Robert pointed out in
the other thread[1], sadly, ATA spec does NOT require cache flush on
standby and some distros don't flush cache prior to put the drive into
standby mode during shutdown. This means that we can't skip cache flush
in the kernel shutdown path because data loss is possible. Also, we
just can't switch to new method because there are drives which spin up
if told to spin down while it's already spun down.
So, that leaves us with migrating to new behavior (kernel side
sync/shutdown) while maintaining backward compatibility. This patchset
tries to do that by supplying a scheduled-to-be-removed module parameter
libata.spindown_compat which defaults to 1. When set, it makes libata
skip spindown during shutdown sequence thus maintaining the old behavior
of issuing only cache flush on shutdown.
So, distros should update their shutdown(8) to do the followings.
* Check whether /sys/modules/libata/parameters/spindown_compat
exists. If it does, write 0 to it.
* For each libata harddisk {
* Check whether /sys/class/scsi_disk/h:c:i:l/manage_start_stop
exists. Iff it doesn't, synchronize cache and spin the disk
down as before.
}
If shutdown(8) does the above, nothing will change on older kernels
(some drives will spin up and have to do emergency unload but they
aren't too many) and everything should work properly on kernels with
spindown_compat or later ones which won't have it. If shutdown(8) isn't
updated, the kernel will behave the same way as older kernels would.
To accelerate userland update, if shutdown(8) isn't updated
(spindown_compat not cleared), libata will complain loudly about it,
point the user to http://linux-ata.org/shutdown.html (which should be
written) and pause for 5 seconds during shutdown. Hopefully, this makes
the users bug distros sufficiently so that userland tools can be updated
quickly. Note that the pausing happens only during shutdown not during
reboot or suspend, so it shouldn't be too much of annoyance.
This change requires sdev->manage_start_stop updates from scsi-misc-2.6.
The merged git tree can be found at...
http://htj.dyndns.org/git/?p=libata-tj.git;a=shortlog;h=spindown
git://htj.dyndns.org/libata-tj spindown
Thanks.
--
tejun
[1] http://thread.gmane.org/gmane.linux.ide/18167
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