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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>
--
"Premature optimization is the root of all evil." - Donald Knuth
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