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What: /sys/firmware/acpi/interrupts/
Date: February 2008
Contact: Len Brown <lenb@kernel.org>
Description:
All ACPI interrupts are handled via a single IRQ,
the System Control Interrupt (SCI), which appears
as "acpi" in /proc/interrupts.
However, one of the main functions of ACPI is to make
the platform understand random hardware without
special driver support. So while the SCI handles a few
well known (fixed feature) interrupts sources, such
as the power button, it can also handle a variable
number of a "General Purpose Events" (GPE).
A GPE vectors to a specified handler in AML, which
can do a anything the BIOS writer wants from
OS context. GPE 0x12, for example, would vector
to a level or edge handler called _L12 or _E12.
The handler may do its business and return.
Or the handler may send send a Notify event
to a Linux device driver registered on an ACPI device,
such as a battery, or a processor.
To figure out where all the SCI's are coming from,
/sys/firmware/acpi/interrupts contains a file listing
every possible source, and the count of how many
times it has triggered.
$ cd /sys/firmware/acpi/interrupts
$ grep . *
error:0
ff_gbl_lock:0
ff_pmtimer:0
ff_pwr_btn:0
ff_rt_clk:0
ff_slp_btn:0
gpe00:0
gpe01:0
gpe02:0
gpe03:0
gpe04:0
gpe05:0
gpe06:0
gpe07:0
gpe08:0
gpe09:174
gpe0A:0
gpe0B:0
gpe0C:0
gpe0D:0
gpe0E:0
gpe0F:0
gpe10:0
gpe11:60
gpe12:0
gpe13:0
gpe14:0
gpe15:0
gpe16:0
gpe17:0
gpe18:0
gpe19:7
gpe1A:0
gpe1B:0
gpe1C:0
gpe1D:0
gpe1E:0
gpe1F:0
gpe_all:241
sci:241
sci - The total number of times the ACPI SCI
has claimed an interrupt.
gpe_all - count of SCI caused by GPEs.
gpeXX - count for individual GPE source
ff_gbl_lock - Global Lock
ff_pmtimer - PM Timer
ff_pwr_btn - Power Button
ff_rt_clk - Real Time Clock
ff_slp_btn - Sleep Button
error - an interrupt that can't be accounted for above.
Root has permission to clear any of these counters. Eg.
# echo 0 > gpe11
All counters can be cleared by clearing the total "sci":
# echo 0 > sci
None of these counters has an effect on the function
of the system, they are simply statistics.
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