Re: -mm swsusp: do not default to platform/firmware

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > -mm swsusp now defaults to platform/firmware suspend... That's
> > > certainly unexpected, changes behaviour from previous version, and
> > > only works on one of three machines I have here. I'd like the default
> > > to be changed back.
> > 
> > You overestimate my knowledge of suspend stuff.  AFAICT the current -mm
> > default is to enter ACPI sleep state via the BIOS rather than via Linux's
> > ACPI driver.  Correct?
> 
> Its actually bit more complex. There are 3 methods:
> 
> shutdown: save state in linux, then tell bios to powerdown
> 
> platform: save state in linux, then tell bios to powerdown and blink
> 	  "suspended led"
> 
> firmware: tell bios to save state itself
> 
> "platform" is actually right thing to do, but "shutdown" is most
> reliable.

...could you apply this? I hope it is accurate.
								Pavel

--- clean/Documentation/power/swsusp.txt	2004-06-22 12:35:44.000000000 +0200
+++ linux/Documentation/power/swsusp.txt	2004-07-29 01:42:29.000000000 +0200
@@ -199,3 +202,30 @@
 should be sent to the mailing list available through the suspend2
 website, and not to the Linux Kernel Mailing List. We are working
 toward merging suspend2 into the mainline kernel.
+
+Q: Kernel thread must voluntarily freeze itself (call 'refrigerator'). But
+I did found some kernel threads don't do it, and they don't freeze, and
+so the system can't sleep. Is this a known behavior?
+
+A: All such kernel threads need to be fixed, one by one. Select place
+where it is safe to be frozen (no kernel semaphores should be held at
+that point and it must be safe to sleep there), and add:
+
+            if (current->flags & PF_FREEZE)
+                    refrigerator(PF_FREEZE);
+
+Q: What is the difference between between "platform", "shutdown" and
+"firmware" in /sys/power/disk?
+
+A:
+
+shutdown: save state in linux, then tell bios to powerdown
+
+platform: save state in linux, then tell bios to powerdown and blink
+          "suspended led"
+
+firmware: tell bios to save state itself [needs BIOS-specific suspend
+	  partition, and has very little to do with swsusp]
+
+"platform" is actually right thing to do, but "shutdown" is most
+reliable.



-- 
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