We continually make progress in this area, and we already can fix a huge number of potential issues. I would rather not allow an option to disable this unless it is absolutely necessary; I don't want this ACPICA feature to become disabled permanently in Linux.
It is rather surprising how many predefined names in any given BIOS return incorrect values. What started out as ad-hoc code littered throughout ACPICA and the ACPI-related device drivers is now encapsulated in a repair module that handles hundreds of possible cases. The repair module is table-driven and causes only a very small overhead.
The final goal of the detect/repair mechanism is that if a driver receives an AE_OK back from the evaluation of a predefined name (anything that starts with an underscore), it is guaranteed that the return value is something that is expected -- thus saving all of the ACPI-related device drivers from performing typechecks on the returned object.
Note: The ACPICA validation/repair code was originally released in 2009.
Bob
> -----Original Message-----
> From: Zheng, Lv
> Sent: Tuesday, January 22, 2013 11:29 PM
> To: Brown, Len; Wysocki, Rafael J; Rafael J Wysocki; Moore, Robert
> Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; Zheng, Lv
> Subject: [RFC PATCH] ACPI: Add boot option to disable auto return object
> repair
>
> There is automatic return object repair mechanism implemented in ACPICA
> which can not handle all of the issues exposed by BIOS currently. This
> patch allow a kernel boots up without such workarounds enabled. A better
> choice should refine the repair mechanism to allow more robust evaluation
> result.
>
> Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
> ---
> drivers/acpi/bus.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index
> 01708a1..e33577f 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -805,6 +805,18 @@ static int __init acpi_bus_init(void) struct kobject
> *acpi_kobj; EXPORT_SYMBOL_GPL(acpi_kobj);
>
> +static int __init acpi_disable_repair(char *s) {
> + printk(KERN_NOTICE PREFIX
> + "ACPI: Predefined names repair disabled\n");
> +
> + acpi_gbl_disable_auto_repair = TRUE;
> +
> + return 1;
> +}
> +
> +__setup("acpi_no_repair", acpi_disable_repair);
> +
> static int __init acpi_init(void)
> {
> int result;
> --
> 1.7.10.4
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