RE: [Acpi] acpi questions (fwd)

From: Grover, Andrew (
Date: Thu Aug 03 2000 - 11:32:10 EST

> From: Garst R. Reese <>
> 1. What do these error messages mean?
> in /var/adm/debug
> This is on an IBM Thinkpad 380D
> Aug 1 22:03:12 aar acpid: ACPI Subsystem version [Jun 1 2000]
> Aug 1 22:03:12 aar acpid: tbutils-0240:
> Aug 1 22:03:12 aar acpid: *** Error: Invalid ACPI table checksum
> Aug 1 22:03:12 aar acpid: nsapinam-0058:
> Aug 1 22:03:12 aar acpid: DSDT is not in memory
> Aug 1 22:03:12 aar acpid: OsdBreakpoint: Fatal error encountered

It means the acpi subsystem was unable to load the tables, apparently due to
an invalid checksum.

> 2. from pm.txt
> "If a working ACPI implementation is found, the
> ACPI driver will override and disable APM, otherwise the APM driver
> will be used."
> What is meant here by -working-

There are a number of tables that the bios provides, which the ACPI
subsystem consumes. These tables have to be laid out properly (checksums
work out, no illegal grammar, etc.) for ACPI to work. It looks like what may
be happening in your case is that your system has some ACPI support (or we
wouldn't be finding any tables) but that they're not correctly formatted.
Just a guess. Does IBM have any bios updates for that machine?

> 3. Does anybody have acpi working to their advantage?

Yep. But, please realize that all the features of ACPI are not fully
implemented yet, i.e. it's still under active development.

> 4. What does DSDT stand for?

Differentiated System Description Table. This is where the motherboard's
resources are described, in Acpi Machine Language (AML).

> 5. Do any of the above error msgs make sense to anybody.

Yep ;-) The interpreter currently in the kernel releases has had most of the
debug output removed, but the plans are to have a patch which reincorporates
these, for debugging.

> 6. Is there any *real* advantage to acpi vs apm?

Basically, APM is bad because the bios is in charge of power management, but
the OS is the one in the system which really has the best idea of what to
do. So, ACPI moves PM into the OS, but still relies on the bios for the
platform specific tables. It's still dependent on the platform bios, but not
as much.

IA64 also requires ACPI support.

> 7. Has it been implemented in *any* drivers?

I don't think so. That's a big job that's coming up.

Regards -- Andy

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