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Date: Tue, 18 Feb 2003 15:41:10 -0600 (CST)
From: Patrick Mochel <mochel@osdl.org>
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To: Pavel Machek <pavel@ucw.cz>
cc: <torvalds@transmeta.com>, kernel list <linux-kernel@vger.kernel.org>,
       ACPI mailing list <acpi-devel@lists.sourceforge.net>
Subject: Re: Fixes to suspend-to-RAM
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On Tue, 18 Feb 2003, Pavel Machek wrote:

> Hi!
> 
> > >  void __init acpi_reserve_bootmem(void)
> > >  {
> > >  	acpi_wakeup_address = (unsigned long)alloc_bootmem_low(PAGE_SIZE);
> > > +	if (!acpi_wakeup_address)
> > > +		printk(KERN_ERR "ACPI: Cannot allocate lowmem. S3 disabled.\n");
> > >  	if ((&wakeup_end - &wakeup_start) > PAGE_SIZE)
> > >  		printk(KERN_CRIT "ACPI: Wakeup code way too big, will crash on attempt to suspend\n");
> > > -	printk(KERN_DEBUG "ACPI: have wakeup address 0x%8.8lx\n", acpi_wakeup_address);
> > 
> > If you say you're disabling S3, then please really do so and flip the bit 
> > in the sleep_states[] array.
> 
> Check the code, there's a conditional former in the file and S3 will
> correctly fail. I don't feel like flipping bits from here
> (arch-dep-code) in generic code.

Fine. But, how about a call that the drivers/acpi/sleep/main.c::sleep_init()
can call to arch/i386/kernel/acpi/ to validate that it can do S3 from the 
beginning. That way, we're more certain of whether or not we're going to 
succeed or not. 

Doing this can also get rid of this crap, too:

int acpi_save_state_mem (void)
{
#if CONFIG_X86_PAE
        panic("S3 and PAE do not like each other for now.");
        return 1;
#endif

> Good idea. So acpi_system_save_state can no longer be called with S5,
> right? That allows quite a lot of cleanup.

Correct.

> Hmm, how do you propose error handling when SUSPEND_DISABLE fails?
> Call SUSPEND_ENABLE or not? Once that is decided  panic can go. But I
> still think that just should not happen.

I propose that we don't even call SUSPEND_DISABLE. Based on recent
conversations, it appears that we can and should do the entire device
suspend sequence in two passes - SUSPEND_SAVE_STATE with interrupts
enabled, and SUSPEND_POWER_DOWN with interrupts disabled.


	-pat

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