On Mon, 2007-11-12 at 17:32 +0100, Johannes Berg wrote:
quoted
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.
Obviously. I don't have any of that. I'd appreciate if somebody could
test on a 3400 powerbook to see if that pci config space save/restore
stuff is really necessary or even interferes with the regular stuff.
Might not be that necessary anymore nowadays, the generic code ought to
do it, but I'll give a go, I have one of those (paulus old one) though
last I tried, the HD was dead.
Ben.
On Tue, 13 Nov 2007, Benjamin Herrenschmidt wrote:
On Mon, 2007-11-12 at 17:32 +0100, Johannes Berg wrote:
quoted
quoted
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