Re: [PATCH 1/5] ACPI Hibernation: Use ACPI hardware signature

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On Wednesday, 11 of June 2008, Rafael J. Wysocki wrote:
> From: Shaohua Li <shaohua.li@xxxxxxxxx>
> 
> ACPI defines a hardware signature.  BIOS calculates the signature
> according to hardware configure and if hardware changes while
> hibernated, the signature will change.  In that case, S4 resume
> should fail.
> 
> Still, there may be systems on which this mechanism does not work
> correctly, so it is better to provide a workaround for them.  For
> this reason, add a new switch to the acpi_sleep= command line
> argument allowing one to disable hardware signature checking.
> 
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
> Acked-by: Pavel Machek <pavel@xxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>

Unfortunately this patch will conflict with the one the Jesse has just put into
his linux-next branch, so please ignore it for now.  I'll repost it during the
2.6.27 cycle.

Thanks,
Rafael


> ---
>  Documentation/kernel-parameters.txt |    4 +++-
>  arch/x86/kernel/acpi/sleep.c        |    2 ++
>  drivers/acpi/sleep/main.c           |   22 ++++++++++++++++++++++
>  include/linux/acpi.h                |    3 +++
>  4 files changed, 30 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/acpi/sleep/main.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/sleep/main.c
> +++ linux-2.6/drivers/acpi/sleep/main.c
> @@ -255,6 +255,15 @@ static struct dmi_system_id __initdata a
>  #endif /* CONFIG_SUSPEND */
>  
>  #ifdef CONFIG_HIBERNATION
> +static unsigned long s4_hardware_signature;
> +static struct acpi_table_facs *facs;
> +static bool nosigcheck;
> +
> +void __init acpi_no_s4_hw_signature(void)
> +{
> +	nosigcheck = true;
> +}
> +
>  static int acpi_hibernation_begin(void)
>  {
>  	acpi_target_sleep_state = ACPI_STATE_S4;
> @@ -301,6 +310,12 @@ static void acpi_hibernation_leave(void)
>  	acpi_enable();
>  	/* Reprogram control registers and execute _BFS */
>  	acpi_leave_sleep_state_prep(ACPI_STATE_S4);
> +	/* Check the hardware signature */
> +	if (facs && s4_hardware_signature != facs->hardware_signature) {
> +		printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
> +			"cannot resume!\n");
> +		panic("ACPI S4 hardware signature mismatch");
> +	}
>  }
>  
>  static void acpi_hibernation_finish(void)
> @@ -501,6 +516,13 @@ int __init acpi_sleep_init(void)
>  		hibernation_set_ops(&acpi_hibernation_ops);
>  		sleep_states[ACPI_STATE_S4] = 1;
>  		printk(" S4");
> +		if (!nosigcheck) {
> +			acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
> +				(struct acpi_table_header **)&facs);
> +			if (facs)
> +				s4_hardware_signature =
> +					facs->hardware_signature;
> +		}
>  	}
>  #endif
>  	status = acpi_get_sleep_type_data(ACPI_STATE_S5, &type_a, &type_b);
> Index: linux-2.6/Documentation/kernel-parameters.txt
> ===================================================================
> --- linux-2.6.orig/Documentation/kernel-parameters.txt
> +++ linux-2.6/Documentation/kernel-parameters.txt
> @@ -147,10 +147,12 @@ and is between 256 and 4096 characters. 
>  			default: 0
>  
>  	acpi_sleep=	[HW,ACPI] Sleep options
> -			Format: { s3_bios, s3_mode, s3_beep }
> +			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig }
>  			See Documentation/power/video.txt for s3_bios and s3_mode.
>  			s3_beep is for debugging; it makes the PC's speaker beep
>  			as soon as the kernel's real-mode entry point is called.
> +			s4_nohwsig prevents ACPI hardware signature from being
> +			used during resume from hibernation.
>  
>  	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
>  			Format: { level | edge | high | low }
> Index: linux-2.6/arch/x86/kernel/acpi/sleep.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/acpi/sleep.c
> +++ linux-2.6/arch/x86/kernel/acpi/sleep.c
> @@ -124,6 +124,8 @@ static int __init acpi_sleep_setup(char 
>  			acpi_realmode_flags |= 2;
>  		if (strncmp(str, "s3_beep", 7) == 0)
>  			acpi_realmode_flags |= 4;
> +		if (strncmp(str, "s4_nohwsig", 10) == 0)
> +			acpi_no_s4_hw_signature();
>  		str = strchr(str, ',');
>  		if (str != NULL)
>  			str += strspn(str, ", \t");
> Index: linux-2.6/include/linux/acpi.h
> ===================================================================
> --- linux-2.6.orig/include/linux/acpi.h
> +++ linux-2.6/include/linux/acpi.h
> @@ -234,6 +234,9 @@ int acpi_check_region(resource_size_t st
>  int acpi_check_mem_region(resource_size_t start, resource_size_t n,
>  		      const char *name);
>  
> +#ifdef CONFIG_PM_SLEEP
> +void __init acpi_no_s4_hw_signature(void);
> +#endif /* CONFIG_PM_SLEEP */
>  #else	/* CONFIG_ACPI */
>  
>  static inline int early_acpi_boot_init(void)
> --
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> 



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