>Number: 160838
>Category: kern
>Synopsis: ACPI Battery Monitor Non-Functional
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Sep 20 04:10:10 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator: Eric McCorkle
>Release: 9.0-CURRENT
>Organization:
>Environment:
FreeBSD atom-edge 9.0-BETA2 FreeBSD 9.0-BETA2 #41: Mon Sep 19 19:02:17 EDT 2011
root@atom-edge:/usr/obj/usr/src/sys/CUSTOM amd64
>Description:
Recently updated sources, which caused acpiconf -i0 to stop reporting
information about the battery properly. Instead, it reports "not present", and
0 for all values, except charge (which reports as -1).
I have already identified the root cause for the problem.
>How-To-Repeat:
The problem should occur on any system with a battery using the cmbat
interface, which dispatches a large number of calls via AcpiOsExecute during
initialization. This fills up the task queue, which results in the call to
acpi_cmbat_init_battery getting dropped due to the queue being full, which
results in the bif information not being properly initialized. Because the
cmbat driver only reads this information at initalization, the driver will
incorrectly report the battery as not being present.
Similar issues with other ACPI features may have a similar root cause.
>Fix:
Setting debug.acpi.max_tasks to a high value (I used 128) is a stable
workaround, and will restore functionality.
>Release-Note:
>Audit-Trail:
>Unformatted:
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