On Sunday, October 10, 2010, James Hogan wrote: > On Sunday 10 October 2010 21:47:19 Pavel Machek wrote: > > On Sun 2010-10-10 20:47:01, James Hogan wrote: > > > Hi Pavel, > > > > > > On Sunday 10 October 2010 19:04:00 Pavel Machek wrote: > > > > Hi! > > > > > > > > > If the device which fails to resume is part of a loadable kernel > > > > > module it won't be checked at startup against the magic number > > > > > stored in the RTC. > > > > > > > > > > Add a read-only sysfs attribute /sys/power/pm_trace_dev_hash which > > > > > contains a list of newline separated devices (usually just the one) > > > > > which currently match the last magic number. This allows the device > > > > > which is failing to resume to be found after the modules are loaded > > > > > again. > > > > > > > > > > --- a/Documentation/power/s2ram.txt > > > > > +++ b/Documentation/power/s2ram.txt > > > > > > > > > > @@ -49,6 +49,13 @@ machine that doesn't boot) is: > > > > > device (lspci and /sys/devices/pci* is your friend), and see if > > > > > you can fix it, disable it, or trace into its resume function. > > > > > > > > > > + If no device matches the hash, it may be a device from a loadable > > > > > kernel + module that is not loaded until after the hash is checked. > > > > > You can check + the hash against the current devices again after > > > > > more modules are loaded + using sysfs: > > > > > + > > > > > + cat /sys/power/pm_trace_dev_hash > > > > > + > > > > > > > > Yep, but exact semantics of that sysfs file should probably be linked > > > > in the sysfs documentation... > > > > > > > > Pavel > > > > > > To clarify, do you mean I should link to > > > Documentation/ABI/testing/sysfs-power from > > > Documentation/power/s2ram.txt, or just make sure the syfs file is > > > documented in Documentation/ABI/testing/sysfs-power (which is done in v2 > > > of this patch)? > > > > v2 of the patch is probably ok. > > > > Also, sysfs should be one entry per file, and strictly speaking, this > > one is not. That may be fine... but as this is debugging facility, > > perhaps it should go to debugfs? Maybe cc gregkh... > > Pavel > > I thought about the one entry per file issue. > Documentation/filesystems/sysfs.txt says: > > It is noted that it may not be efficient to contain only one > > value per file, so it is socially acceptable to express an array of > > values of the same type. > > which appears to cover my use of it as they're all the same type (and > considering that ideally there will be exactly 1 device listed anyway). > > I wonder if I should separate them with spaces rather than newlines too > (newlines just seemed more appropriate for a variable sized list at the time). > > I ackowledge your point that debugfs may be a more appropriate place for it, > but would that also apply to the pm_trace file? Yes, it would. Let's keep the things cosistent, ie. v2 of your patch is fine and I'm going to apply it. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
