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-What: /sys/firmware/acpi/bgrt/
-Date: January 2012
-Contact: Matthew Garrett <mjg@redhat.com>
-Description:
- The BGRT is an ACPI 5.0 feature that allows the OS
- to obtain a copy of the firmware boot splash and
- some associated metadata. This is intended to be used
- by boot splash applications in order to interact with
- the firmware boot splash in order to avoid jarring
- transitions.
-
- image: The image bitmap. Currently a 32-bit BMP.
- status: 1 if the image is valid, 0 if firmware invalidated it.
- type: 0 indicates image is in BMP format.
- version: The version of the BGRT. Currently 1.
- xoffset: The number of pixels between the left of the screen
- and the left edge of the image.
- yoffset: The number of pixels between the top of the screen
- and the top edge of the image.
-
-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 enable
- ff_pmtimer: 0 invalid
- ff_pwr_btn: 0 enable
- ff_rt_clk: 2 disable
- ff_slp_btn: 0 invalid
- gpe00: 0 invalid
- gpe01: 0 enable
- gpe02: 108 enable
- gpe03: 0 invalid
- gpe04: 0 invalid
- gpe05: 0 invalid
- gpe06: 0 enable
- gpe07: 0 enable
- gpe08: 0 invalid
- gpe09: 0 invalid
- gpe0A: 0 invalid
- gpe0B: 0 invalid
- gpe0C: 0 invalid
- gpe0D: 0 invalid
- gpe0E: 0 invalid
- gpe0F: 0 invalid
- gpe10: 0 invalid
- gpe11: 0 invalid
- gpe12: 0 invalid
- gpe13: 0 invalid
- gpe14: 0 invalid
- gpe15: 0 invalid
- gpe16: 0 invalid
- gpe17: 1084 enable
- gpe18: 0 enable
- gpe19: 0 invalid
- gpe1A: 0 invalid
- gpe1B: 0 invalid
- gpe1C: 0 invalid
- gpe1D: 0 invalid
- gpe1E: 0 invalid
- gpe1F: 0 invalid
- gpe_all: 1192
- sci: 1194
- sci_not: 0
-
- sci - The number of times the ACPI SCI
- has been called and claimed an interrupt.
-
- sci_not - The number of times the ACPI SCI
- has been called and NOT 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.
-
- invalid: it's either a GPE or a Fixed Event that
- doesn't have an event handler.
-
- disable: the GPE/Fixed Event is valid but disabled.
-
- enable: the GPE/Fixed Event is valid and enabled.
-
- 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.
-
- Besides this, user can also write specific strings to these files
- to enable/disable/clear ACPI interrupts in user space, which can be
- used to debug some ACPI interrupt storm issues.
-
- Note that only writting to VALID GPE/Fixed Event is allowed,
- i.e. user can only change the status of runtime GPE and
- Fixed Event with event handler installed.
-
- Let's take power button fixed event for example, please kill acpid
- and other user space applications so that the machine won't shutdown
- when pressing the power button.
- # cat ff_pwr_btn
- 0 enabled
- # press the power button for 3 times;
- # cat ff_pwr_btn
- 3 enabled
- # echo disable > ff_pwr_btn
- # cat ff_pwr_btn
- 3 disabled
- # press the power button for 3 times;
- # cat ff_pwr_btn
- 3 disabled
- # echo enable > ff_pwr_btn
- # cat ff_pwr_btn
- 4 enabled
- /*
- * this is because the status bit is set even if the enable bit is cleared,
- * and it triggers an ACPI fixed event when the enable bit is set again
- */
- # press the power button for 3 times;
- # cat ff_pwr_btn
- 7 enabled
- # echo disable > ff_pwr_btn
- # press the power button for 3 times;
- # echo clear > ff_pwr_btn /* clear the status bit */
- # echo disable > ff_pwr_btn
- # cat ff_pwr_btn
- 7 enabled
-