New subject: [Bug 58401] system.fill_battery_state: support battery drivers that expose energy_* instead of charge_* attributes of power_supply_class

20 Jun 2025


      http://bugs.winehq.org/show_bug.cgi?id=58401
Bug ID: 58401
           Summary: system.fill_battery_state: support battery drivers
                    that expose energy_* instead of charge_*  attributes
                    of power_supply_class
           Product: Wine
           Version: 10.10
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: ntdll
          Assignee: wine-bugs@winehq.org
          Reporter: rtdiasmendes@gmail.com
      Distribution: ---
File: system.c
Method: fill_battery_state( SYSTEM_BATTERY_STATE *bs )
Current implementation:
 - Assumes battery driver exposes: "charge_now", "charge_full", "voltage_now"
and "current_now".
 - Populates SYSTEM_BATTERY_STATE with those attributes after converting to
expected units
Issue:
 - Some battery drivers expose different ABI-compliant attributes 
 - In systems with those drivers, Wine is incapable of emulating windows
behaviour
Enhacement proposal:
 - Add support for drivers that expose different attributes
Further reading:
 - https://docs.kernel.org/power/power_supply_class.html
 - https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power
 - https://github.com/torvalds/linux/blob/master/include/linux/power_supply.h
 -
https://github.com/torvalds/linux/blob/master/drivers/power/supply/power_sup...
Note:
Attribute "scope", while implemented in the kernel, is undocumented in the
power_supply_class docs. Will later check if the rest of the documentation is
up to date and raise the appropriate issue upstream. Until then, do not assume
it correctly reflects the kernel implementation.
Out-of-scope commentary:
While Wine's behavior of querying /sys/class/power_supply/ on every
NtPowerInformation() call correctly emulates the Windows API semantics, it has
unintended performance implications on Linux. This is due to the fact that
retrieving battery information from sysfs involves real filesystem I/O,
including frequent failed lookups on systems that expose energy_* instead of
charge_* attributes.
Therefore, applications may call NtPowerInformation() without prioritizing
caching or proper fallback logic as they expect the operation to have a
lower-cost then it does on Linux - causing significant and unnecessary
performance degradation.
This may merit its own enhacement proposal if it results in noticeable
performance degradation.
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[Bug 58401] New: system.fill_battery_state: support battery drivers that expose energy_* instead of charge_* attributes of power_supply_class