On Tue, 13 Nov 2007, Benjamin Herrenschmidt wrote: > > On Mon, 2007-11-12 at 17:32 +0100, Johannes Berg wrote: > > > Looks good to me, +/- a couple of things: > > > > > > - We _REALLY_ want the freezer to be optional and not enabled by > > > default on PowerPC. Maybe make it a compile option ? > > > > Well, Alan is going to tell you that USB will break. If we need > > confirmation for that I can do the test he suggested to you or Paul a > > while ago. > > Then USB is broken today on powermacs and need to be fixed. We had a > clear agreement at KS this year that the freezer was at best a band-aid > and that drivers -had- to be fixed to cope regardless. More accurately, freezing user tasks is at best a band-aid. However some kernel threads do need to be frozen, and keeping the freezer around for their use makes sense. It has less overhead -- I think -- than adding new code to do the freezing in each of these threads. (It's true that USB drivers in general aren't written to operate in a freezerless system-suspend environment. That's a harder problem and it will have to be fixed driver-by-driver, over time. The same may be true for lots of non-USB char device drivers as well. Pick your favorite char device driver: How will it behave if a user task submits an I/O request after the device has been suspended?) Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
