kern/124223: [acpi] [patch] acpi_battery.c -- Notify user-defined critical level via devd(8)

Pietro Cerutti gahr at
Mon Sep 8 22:14:23 UTC 2008

Hash: SHA512

Nate Lawson wrote:
| Pietro Cerutti wrote:
|> Nate Lawson wrote:
|> | There are a few problems with your approach.
|> |
|> | Critical status is already reported with a flag when usermode polls for
|> | the battery status:
|> |> if (sc->bst.state & ACPI_BATT_STAT_CRITICAL) {
|> |>     if ((sc->flags & ACPI_BATT_STAT_CRITICAL) == 0) {
|> |>         sc->flags |= ACPI_BATT_STAT_CRITICAL;
|> |>         device_printf(dev, "critically low charge!\n");
|> |>     }
|> |> }
|> I agree. Critical level is already checked for in the cmbat module.
|> However, reporting is not done in a "standardized" way. My patch would
|> just like to add notification through devd.
| But it doesn't just add notification through devd.  It adds a thread,
| that separately polls for battery state and sends a notify through devd.
|  If the user is running any battery app, there's a double poll for the
| same info.
| I subscribe to the design approach that where it makes sense to do
| something in usermode, don't do it in kernel mode.  In this case, the IO
| interface is poll-only, and any user app that is running can set its own
| policy for how to deal with the information it gets from polling.

[snip xbatt-related stuff]

| Let's keep this in usermode, where policy belongs.

That's fine. Thanks for reviewing that!


- --
Pietro Cerutti
gahr at

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