Re: [PATCH v3 1/2] ACPI: Cleanup to convert acpi.no_static_ssdt into a compile-time configurable.

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Monday, May 12, 2014 03:49:59 PM Lv Zheng wrote:
> User can specify a DSDT with SSDT embedded, in which case, no_static_ssdt
> must be enforced during compile-time.  If we don't do that and forget to
> specify acpi.no_static_ssdt as a boot parameter, then:
> 1. The AML executable will be executed twice, the second execution is
>    running under a changed environment.
> 2. The namespace object conflicts will result in an AE_ALREADY_EXISTS
>    exception;
> 3. The namespace objects that are deleted from the original SSDT will be
>    restored by the auto loading of the original SSDT.
> 
> Note that:
> 1. The DSDT customization is a compile-time feature, thus the SSDT
>    inclusion indication of the DSDT customization should also be
>    implemented as a compile-time configurable.
> 2. According to the commit log:
>     Commit: 67effe8fff32f60bdf51cba484766ba6003005bb
>     Subject: ACPI: add "acpi_no_auto_ssdt" bootparam
>    The acpi.no_static_ssdt (originally acpi.no_auto_ssdt) was introduced to
>    be used for this use case.  And over a long time, there is no other
>    situation than this requires this boot parameter.
> This patch thus converts the runtime kernel parameter into the compile-time
> configuration item.
> 
> References: https://bugzilla.kernel.org/show_bug.cgi?id=3774
> Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=69711
> Original-by: Enrico Etxe Arte <goitizena.generoa@gmail.com>
> Signed-off-by: Lv Zheng <lv.zheng@intel.com>
> ---
>  Documentation/kernel-parameters.txt |   10 ----------
>  drivers/acpi/Kconfig                |   32 ++++++++++++++++++++++++++------
>  drivers/acpi/internal.h             |    5 +++++
>  drivers/acpi/osl.c                  |    8 +++-----
>  drivers/acpi/tables.c               |    2 ++
>  5 files changed, 36 insertions(+), 21 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 831fb1e..ceba0d6 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -237,16 +237,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			This feature is enabled by default.
>  			This option allows to turn off the feature.
>  
> -	acpi_no_static_ssdt	[HW,ACPI]
> -			Disable installation of static SSDTs at early boot time
> -			By default, SSDTs contained in the RSDT/XSDT will be
> -			installed automatically and they will appear under
> -			/sys/firmware/acpi/tables.
> -			This option turns off this feature.
> -			Note that specifying this option does not affect
> -			dynamic table installation which will install SSDT
> -			tables to /sys/firmware/acpi/tables/dynamic.
> -
>  	acpica_no_return_repair [HW, ACPI]
>  			Disable AML predefined validation mechanism
>  			This mechanism can repair the evaluation result to make
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index c0160bb..51dc3b8 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -216,22 +216,40 @@ config ACPI_NUMA
>  	depends on (X86 || IA64)
>  	default y if IA64_GENERIC || IA64_SGI_SN2
>  
> -config ACPI_CUSTOM_DSDT_FILE
> -	string "Custom DSDT Table file to include"
> -	default ""
> +menu "Table override"
> +
> +menuconfig ACPI_CUSTOM_DSDT

I would make this a choice, like the "Kernel compression mode" (in init/Kconfig).

Then ACPI_CUSTOM_DSDT_ONLY and ACPI_CUSTOM_DSDT_WITH_SSDT may be the options
and they both would select ACPI_CUSTOM_DSDT (otherwise invisible to the user), and ->

> +	bool "Customize DSDT"
>  	depends on !STANDALONE
>  	help
>  	  This option supports a custom DSDT by linking it into the kernel.
>  	  See Documentation/acpi/dsdt-override.txt
>  
> +	  If unsure, say N.
> +
> +if ACPI_CUSTOM_DSDT
> +
> +config ACPI_CUSTOM_DSDT_FILE

-> this would work for both.

Would that make sense?

> +	string "Custom DSDT Table file to include"
> +	default ""
> +	help
>  	  Enter the full path name to the file which includes the AmlCode
>  	  declaration.
>  
>  	  If unsure, don't enter a file name.
>  
> -config ACPI_CUSTOM_DSDT
> -	bool
> -	default ACPI_CUSTOM_DSDT_FILE != ""
> +config ACPI_CUSTOM_DSDT_WITH_SSDT
> +	bool "Customize DSDT with static SSDTs included"
> +	depends on ACPI_CUSTOM_DSDT
> +	help
> +	  This option allows a DSDT override to optionally be a DSDT+SSDT
> +	  override.  In which case, Linux should stop loading static SSDTs
> +          from RSDT/XSDT.  Otherwise, the load time AML execution of the
> +	  SSDTs will be errornously executed twice.
> +
> +	  If unsure, say N.
> +
> +endif
>  
>  config ACPI_INITRD_TABLE_OVERRIDE
>  	bool "ACPI tables override via initrd"
> @@ -243,6 +261,8 @@ config ACPI_INITRD_TABLE_OVERRIDE
>  	  initrd, therefore it's safe to say Y.
>  	  See Documentation/acpi/initrd_table_override.txt for details
>  
> +endmenu
> +
>  config ACPI_DEBUG
>  	bool "Debug Statements"
>  	default n
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 9573913..f84ef59 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -57,6 +57,11 @@ void acpi_cmos_rtc_init(void);
>  #else
>  static inline void acpi_cmos_rtc_init(void) {}
>  #endif
> +#ifdef CONFIG_ACPI_CUSTOM_DSDT_WITH_SSDT
> +void __init acpi_ssdt_customized(void);
> +#else
> +static inline void acpi_ssdt_customized(void) {}
> +#endif
>  
>  extern bool acpi_force_hot_remove;
>  
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index 9aeae41..c6024c2 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -1770,15 +1770,13 @@ acpi_status acpi_os_release_object(acpi_cache_t * cache, void *object)
>  }
>  #endif
>  
> -static int __init acpi_no_static_ssdt_setup(char *s)
> +#ifdef CONFIG_ACPI_CUSTOM_DSDT_WITH_SSDT
> +void __init acpi_ssdt_customized(void)
>  {
>  	acpi_gbl_disable_ssdt_table_install = TRUE;
>  	pr_info("ACPI: static SSDT installation disabled\n");
> -
> -	return 0;
>  }
> -
> -early_param("acpi_no_static_ssdt", acpi_no_static_ssdt_setup);
> +#endif
>  
>  static int __init acpi_disable_return_repair(char *s)
>  {
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index 2178229..aaf2177 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -184,6 +184,7 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
>  	}
>  }
>  
> +#include "internal.h"
>  
>  int __init
>  acpi_table_parse_entries(char *id,
> @@ -333,6 +334,7 @@ int __init acpi_table_init(void)
>  {
>  	acpi_status status;
>  
> +	acpi_ssdt_customized();
>  	status = acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
>  	if (ACPI_FAILURE(status))
>  		return -EINVAL;
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.