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.
Setting debug.acpi.max_tasks to a high value (I used 128) is a stable workaround, and will restore functionality.
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.
Over to maintainer(s).
As far as I can tell, this issue should be fixed after
increased the MAX_TASKS value.
If so, we can close this one.