Re: [PATCH] i386: Do not restore reserved memory after hibernation

[Andrey Borzenkov <arvidjaar@mail.ru>]

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On Friday 01 June 2007, Rafael J. Wysocki wrote:
> Hi,
>
> This patch is designed to fix
> http://bugzilla.kernel.org/show_bug.cgi?id=7995
>
> Unfortunately, the reporter is unresponsive, 

well, we have our life too ...

I confirm that this patch works. Unfortunately 2.6.22-rc here tends to hang on 
resume from STD often enough to be annoying so I tend to avoid it for daily 
use. It just sits there with cursor in upper left corner, no output on 
screen, nothing. I believe to have seen discussion about USB deadlock during 
resume but cannot find it anymore. The problem is sporadic enough to render 
bisect useless.

-andrey

> so it hasn't been explicitly 
> confirmed to fix the issue, but it's based on some previous patches that
> worked and definitely does what it's meant to do. :-)
>
> Greetings,
> Rafael
>
> ---
> From: Rafael J. Wysocki <rjw@sisk.pl>
>
> On some systems the ACPI NVS area is located in the first 1 MB of RAM and
> it is overwritten by the i386 code during the restore after hibernation.
> This confuses the ACPI platform firmware that doesn't update the AC adapter
> status appropriately as a result
> (http://bugzilla.kernel.org/show_bug.cgi?id=7995).
>
> The solution is to register the reserved memory in the first 1 MB as
> 'nosave', so that swsusp doesn't touch it during the restore.  Also, this
> has been done on x86_64 for a long time now, so the patch makes the i386
> restore behaviour equivalent to the one of x86_64.
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>  arch/i386/kernel/e820.c  |   30 ++++++++++++++++++++++++++++++
>  arch/i386/kernel/setup.c |    1 +
>  include/asm-i386/e820.h  |    1 +
>  3 files changed, 32 insertions(+)
>
> Index: linux-2.6.22-rc3/arch/i386/kernel/e820.c
> ===================================================================
> --- linux-2.6.22-rc3.orig/arch/i386/kernel/e820.c
> +++ linux-2.6.22-rc3/arch/i386/kernel/e820.c
> @@ -10,6 +10,7 @@
>  #include <linux/efi.h>
>  #include <linux/pfn.h>
>  #include <linux/uaccess.h>
> +#include <linux/suspend.h>
>
>  #include <asm/pgtable.h>
>  #include <asm/page.h>
> @@ -320,6 +321,35 @@ static int __init request_standard_resou
>
>  subsys_initcall(request_standard_resources);
>
> +/**
> + * e820_mark_nosave_regions - Find the ranges of physical addresses that
> do not + * correspond to e820 RAM areas and mark the corresponding pages as
> nosave for + * hibernation.
> + *
> + * 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))
> +			register_nosave_region(pfn, PFN_UP(ei->addr));
> +
> +		pfn = PFN_DOWN(ei->addr + ei->size);
> +		if (ei->type != E820_RAM)
> +			register_nosave_region(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-2.6.22-rc3/arch/i386/kernel/setup.c
> ===================================================================
> --- linux-2.6.22-rc3.orig/arch/i386/kernel/setup.c
> +++ linux-2.6.22-rc3/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-2.6.22-rc3/include/asm-i386/e820.h
> ===================================================================
> --- linux-2.6.22-rc3.orig/include/asm-i386/e820.h
> +++ linux-2.6.22-rc3/include/asm-i386/e820.h
> @@ -44,6 +44,7 @@ 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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