Re: [patch] suspend: update warnings

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > + * If you have unsupported (*) devices using DMA, you may have some
> > + * problems. If your disk driver does not support suspend... (IDE does),
> > + * it may cause some problems, too. If you change kernel command line 
> > + * between suspend and resume, it may do something wrong. If you change 
> > + * your hardware while system is suspended... well, it was not good idea;
> > + * but it wil probably only crash.
> 
> The most common driver issues I see involve:
> - USB being built in or as modules that are still loaded while
> suspending (getting better, but not there yet)
> - DRI being used in X where the drivers don't properly support
> suspend/resume (NVidia esp)
> - Firewire
> - CPU Freq  (improving too)
> 
> It might be good to mention these areas too.

Well, right; but those 'only' cause system to crash during suspend. I
was talking about really dangerous stuff.

Both usb and cpufreq seems to work okay here.

I've added FAQ entry at the end:

Q: What information is usefull for debugging suspend-to-disk problems?

A: Well, last messages on the screen are always useful. If something
is broken, it is usually some kernel driver, therefore trying with as
little as possible modules loaded helps a lot. I also prefer people to
suspend from console, preferably without X running. Booting with
init=/bin/bash, then swapon and starting suspend sequence manually
usually does the trick. Then it is good idea to try with latest
vanilla kernel.

"Known problematic" modules are; be sure to unload them before
suspend:
- DRI being used in X where the drivers don't properly support
suspend/resume (NVidia esp)
- Firewire
- SCSI


> Perhaps the 'changing your hardware' could mention that replacing faulty
> hardware may be safe.

I do not want to encourage people to do that. Yep, its probably safe,
no, I do not want them to know.

									Pavel
-- 
if you have sharp zaurus hardware you don't need... you know my address
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