Date:	Thu, 8 Mar 2007 10:51:42 +0300
From:	Andrey Borzenkov <arvidjaar@...l.ru>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...l.org>, Pavel Machek <pavel@....cz>
Subject: Re: 2.6.19: ACPI reports AC not present after resume from STD

On Tuesday 06 March 2007, Rafael J. Wysocki wrote:
> [changed Cc list]
>
> On Sunday, 25 February 2007 18:14, Andrey Borzenkov wrote:
> > On Воскресенье 25 февраля 2007, Rafael J. Wysocki wrote:
> > > On Sunday, 25 February 2007 11:37, Andrey Borzenkov wrote:
> > > > On Воскресенье 25 февраля 2007, Rafael J. Wysocki wrote:
> > > > > On Sunday, 25 February 2007 00:26, Andrey Borzenkov wrote:
> > > > > > On Суббота 24 февраля 2007, Rafael J. Wysocki wrote:
> > > > > > > Hi,
> > > > > > >
> > > > > > > On Saturday, 24 February 2007 10:55, Andrey Borzenkov wrote:
> > > > > > > > On Вторник 13 февраля 2007, Andrey Borzenkov wrote:
> > > > > > > > > On Четверг 07 декабря 2006, Lebedev, Vladimir P wrote:
> > > > > > > > > > Please register new bug, attach acpidump and dmesg.
> > > > > > > > >
> > > > > > > > > http://bugzilla.kernel.org/show_bug.cgi?id=7995
> > > > > > > > >
> > > > > > > > > regards
> > > > > > > >
> > > > > > > > Well, this starts looking like ACPI is not at fault.
> > > > > > > >
> > > > > > > > When reporting AC state ACPI just reads contents of system
> > > > > > > > memory (I presume it gets updated by BIOS/ACPI when AC state
> > > > > > > > changes). It looks like this memory area is restored during
> > > > > > > > resume from STD. I updated mentioned bug report with more
> > > > > > > > detailed description. Now if someone could suggest a way to
> > > > > > > > catch if specific physical address gets saved/restored this
> > > > > > > > would finally explain it.
> > > > > > >
> > > > > > > First, if you want the reserved memory areas to be left alone
> > > > > > > by swsusp, you need to mark them as 'nosave'.  On x86_64 this
> > > > > > > is done by the function e820_mark_nosave_range() in
> > > > > > > arch/x86_64/kernel/e820.c that can be ported to i386 with no
> > > > > > > problems.  However, we haven't found that very useful, so far,
> > > > > > > since no one has ever reported any problems with the current
> > > > > > > approach, which is to save and restore them.
> > > > > >
> > > > > > Well, the following proof of concept patch fixes this issue for
> > > > > > me. Please notice that original version of
> > > > > > e820_mark_nosave_range() could fail to exclude some areas due to
> > > > > > alignment issues (exactly what happened to me on first try) so it
> > > > > > still can explain your problem too.
> > > > >
> > > > > Great job, thanks for the patch!  It looks good, so I'm going to
> > > > > forward it for merging.
> > > >
> > > > Please no; I'm currently testing slightly more polished version; I
> > > > will send it later.
> > >
> > > OK
> > >
> > > > Could anybody explain (or give pointer to) what happens which region
> > > > that is not page-aligned? In particular, the very first one:
> > > >
> > > >  BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> > > >  BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> > > >
> > > > Will the kernel allocate partial page (how?) or will the kernel
> > > > ignore last (first) incomplete page? In the former case how those
> > > > incomplete pages can be detected?
> > >
> > > Well, on x86_64, if I understand e820_register_active_regions()
> > > correctly, the partial pages won't be registered.
> >
> > It appears that for low memory kernel will ignore incomplete pages for
> > sure. I hope it does the same for high memory - but for now I just throw
> > this in and pray :) This also significantly simplifies patch.
>
> Well, can you please check if the appended modification of your patch still
> works?
>

It works for me with caveat

/home/bor/src/linux-git/arch/i386/kernel/e820.c: In 
function ‘e820_mark_nosave_range’:
/home/bor/src/linux-git/arch/i386/kernel/e820.c:328: warning: format ‘%016Lx’ 
expects type ‘long long unsigned int’, but argument 2 has type ‘long unsigned 
int’
/home/bor/src/linux-git/arch/i386/kernel/e820.c:328: warning: format ‘%016Lx’ 
expects type ‘long long unsigned int’, but argument 3 has type ‘long unsigned 
int’

regards 

-andrey

> Thanks,
> Rafael
>
>
> ---
>  arch/i386/kernel/e820.c  |   47
> +++++++++++++++++++++++++++++++++++++++++++++++ arch/i386/kernel/setup.c | 
>   1 +
>  include/asm-i386/e820.h  |    1 +
>  3 files changed, 49 insertions(+)
>
> Index: linux-2.6.21-rc2/arch/i386/kernel/e820.c
> ===================================================================
> --- linux-2.6.21-rc2.orig/arch/i386/kernel/e820.c
> +++ linux-2.6.21-rc2/arch/i386/kernel/e820.c
> @@ -313,6 +313,53 @@ static int __init request_standard_resou
>
>  subsys_initcall(request_standard_resources);
>
> +/*
> + * Mark pages corresponding to given pfn range as 'nosave'.
> + */
> +static void __init
> +e820_mark_nosave_range(unsigned long start_pfn, unsigned long end_pfn)
> +{
> +	unsigned long pfn;
> +
> +	if (start_pfn >= end_pfn)
> +		return;
> +
> +	printk("Nosave address range: %016Lx - %016Lx\n",
> +				PFN_PHYS(start_pfn), PFN_PHYS(end_pfn));
> +	for (pfn = start_pfn; pfn < end_pfn; pfn++)
> +		if (pfn_valid(pfn))
> +			SetPageNosave(pfn_to_page(pfn));
> +}
> +
> +/*
> + * Find the ranges of physical addresses that do not correspond to
> + * e820 RAM areas and mark the corresponding pages as nosave for software
> + * suspend and suspend to RAM.
> + *
> + * This function requires the e820 map to be sorted and without any
> + * overlapping entries and assumes the first e820 area to be RAM.
> + */
> +void __init e820_mark_nosave_regions(void)
> +{
> +	int i;
> +	unsigned long pfn;
> +
> +	pfn = PFN_DOWN(e820.map[0].addr + e820.map[0].size);
> +	for (i = 1; i < e820.nr_map; i++) {
> +		struct e820entry *ei = &e820.map[i];
> +
> +		if (pfn < PFN_UP(ei->addr))
> +			e820_mark_nosave_range(pfn, PFN_UP(ei->addr));
> +
> +		pfn = PFN_DOWN(ei->addr + ei->size);
> +		if (ei->type != E820_RAM)
> +			e820_mark_nosave_range(PFN_UP(ei->addr), pfn);
> +
> +		if (pfn >= max_low_pfn)
> +			break;
> +	}
> +}
> +
>  void __init add_memory_region(unsigned long long start,
>  			      unsigned long long size, int type)
>  {
> Index: linux-2.6.21-rc2/arch/i386/kernel/setup.c
> ===================================================================
> --- linux-2.6.21-rc2.orig/arch/i386/kernel/setup.c
> +++ linux-2.6.21-rc2/arch/i386/kernel/setup.c
> @@ -648,6 +648,7 @@ void __init setup_arch(char **cmdline_p)
>  #endif
>
>  	e820_register_memory();
> +	e820_mark_nosave_regions();
>
>  #ifdef CONFIG_VT
>  #if defined(CONFIG_VGA_CONSOLE)
> Index: linux-2.6.21-rc2/include/asm-i386/e820.h
> ===================================================================
> --- linux-2.6.21-rc2.orig/include/asm-i386/e820.h
> +++ linux-2.6.21-rc2/include/asm-i386/e820.h
> @@ -43,6 +43,7 @@ extern void register_bootmem_low_pages(u
>  extern void e820_register_memory(void);
>  extern void limit_regions(unsigned long long size);
>  extern void print_memory_map(char *who);
> +extern void e820_mark_nosave_regions(void);
>
>  #endif/*!__ASSEMBLY__*/



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