Re: [linux-pm] Re: Hibernation considerations

Am Samstag 21 Juli 2007 schrieb Alan Stern:
On Fri, 20 Jul 2007, Oliver Neukum wrote:

We already have a pre-suspend notification available for drivers that
need to allocate large amounts of memory.

Is that facility fine grained enough?

It's a notifier chain that gets called at several points during the
suspend transition. One of those points is right at the start, while
userspace is still running and reasonably large amounts of memory can
be allocated.

Is it fine-grained enough? I don't know -- hard to tell, since nothing
much is using it yet.

You are correct about the need to delay/stop device addition. I don't
know how this can be done in general; each code path calling
device_add() may have to be treated individually.

What about the old API?

What old API do you mean?

The find_device() stuff.

Do we have to block module loading?

No. Registering new drivers is okay, registering new devices is bad.

What if it is a driver for virtual devices that don't need probe()
for actual hardware?

Of course, some modules do want to register a new device in their init
method. I don't know what we should do about them. Force the
registration to fail, I suppose. How often will people suspend while a
module is loading?

What happens if a scsi error handler is woken? If it cannot be woken,
how are errors handled?

Why should the error handler wake up? There isn't supposed to be any
I/O going on, hence no errors to handle.

What about shared busses? Firewire, FibreChannel? They can get external
resets, etc ...

Regards
Oliver
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