1What: /sys/firmware/acpi/bgrt/ 2Date: January 2012 3Contact: Matthew Garrett <mjg@redhat.com> 4Description: 5 The BGRT is an ACPI 5.0 feature that allows the OS 6 to obtain a copy of the firmware boot splash and 7 some associated metadata. This is intended to be used 8 by boot splash applications in order to interact with 9 the firmware boot splash in order to avoid jarring 10 transitions. 11 12 image: The image bitmap. Currently a 32-bit BMP. 13 status: 1 if the image is valid, 0 if firmware invalidated it. 14 type: 0 indicates image is in BMP format. 15 version: The version of the BGRT. Currently 1. 16 xoffset: The number of pixels between the left of the screen 17 and the left edge of the image. 18 yoffset: The number of pixels between the top of the screen 19 and the top edge of the image. 20 21What: /sys/firmware/acpi/hotplug/ 22Date: February 2013 23Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 24Description: 25 There are separate hotplug profiles for different classes of 26 devices supported by ACPI, such as containers, memory modules, 27 processors, PCI root bridges etc. A hotplug profile for a given 28 class of devices is a collection of settings defining the way 29 that class of devices will be handled by the ACPI core hotplug 30 code. Those profiles are represented in sysfs as subdirectories 31 of /sys/firmware/acpi/hotplug/. 32 33 The following setting is available to user space for each 34 hotplug profile: 35 36 enabled: If set, the ACPI core will handle notifications of 37 hotplug events associated with the given class of 38 devices and will allow those devices to be ejected with 39 the help of the _EJ0 control method. Unsetting it 40 effectively disables hotplug for the correspoinding 41 class of devices. 42 43 The value of the above attribute is an integer number: 1 (set) 44 or 0 (unset). Attempts to write any other values to it will 45 cause -EINVAL to be returned. 46 47What: /sys/firmware/acpi/hotplug/force_remove 48Date: May 2013 49Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 50Description: 51 The number in this file (0 or 1) determines whether (1) or not 52 (0) the ACPI subsystem will allow devices to be hot-removed even 53 if they cannot be put offline gracefully (from the kernel's 54 viewpoint). That number can be changed by writing a boolean 55 value to this file. 56 57What: /sys/firmware/acpi/interrupts/ 58Date: February 2008 59Contact: Len Brown <lenb@kernel.org> 60Description: 61 All ACPI interrupts are handled via a single IRQ, 62 the System Control Interrupt (SCI), which appears 63 as "acpi" in /proc/interrupts. 64 65 However, one of the main functions of ACPI is to make 66 the platform understand random hardware without 67 special driver support. So while the SCI handles a few 68 well known (fixed feature) interrupts sources, such 69 as the power button, it can also handle a variable 70 number of a "General Purpose Events" (GPE). 71 72 A GPE vectors to a specified handler in AML, which 73 can do a anything the BIOS writer wants from 74 OS context. GPE 0x12, for example, would vector 75 to a level or edge handler called _L12 or _E12. 76 The handler may do its business and return. 77 Or the handler may send send a Notify event 78 to a Linux device driver registered on an ACPI device, 79 such as a battery, or a processor. 80 81 To figure out where all the SCI's are coming from, 82 /sys/firmware/acpi/interrupts contains a file listing 83 every possible source, and the count of how many 84 times it has triggered. 85 86 $ cd /sys/firmware/acpi/interrupts 87 $ grep . * 88 error: 0 89 ff_gbl_lock: 0 enable 90 ff_pmtimer: 0 invalid 91 ff_pwr_btn: 0 enable 92 ff_rt_clk: 2 disable 93 ff_slp_btn: 0 invalid 94 gpe00: 0 invalid 95 gpe01: 0 enable 96 gpe02: 108 enable 97 gpe03: 0 invalid 98 gpe04: 0 invalid 99 gpe05: 0 invalid 100 gpe06: 0 enable 101 gpe07: 0 enable 102 gpe08: 0 invalid 103 gpe09: 0 invalid 104 gpe0A: 0 invalid 105 gpe0B: 0 invalid 106 gpe0C: 0 invalid 107 gpe0D: 0 invalid 108 gpe0E: 0 invalid 109 gpe0F: 0 invalid 110 gpe10: 0 invalid 111 gpe11: 0 invalid 112 gpe12: 0 invalid 113 gpe13: 0 invalid 114 gpe14: 0 invalid 115 gpe15: 0 invalid 116 gpe16: 0 invalid 117 gpe17: 1084 enable 118 gpe18: 0 enable 119 gpe19: 0 invalid 120 gpe1A: 0 invalid 121 gpe1B: 0 invalid 122 gpe1C: 0 invalid 123 gpe1D: 0 invalid 124 gpe1E: 0 invalid 125 gpe1F: 0 invalid 126 gpe_all: 1192 127 sci: 1194 128 sci_not: 0 129 130 sci - The number of times the ACPI SCI 131 has been called and claimed an interrupt. 132 133 sci_not - The number of times the ACPI SCI 134 has been called and NOT claimed an interrupt. 135 136 gpe_all - count of SCI caused by GPEs. 137 138 gpeXX - count for individual GPE source 139 140 ff_gbl_lock - Global Lock 141 142 ff_pmtimer - PM Timer 143 144 ff_pwr_btn - Power Button 145 146 ff_rt_clk - Real Time Clock 147 148 ff_slp_btn - Sleep Button 149 150 error - an interrupt that can't be accounted for above. 151 152 invalid: it's either a GPE or a Fixed Event that 153 doesn't have an event handler. 154 155 disable: the GPE/Fixed Event is valid but disabled. 156 157 enable: the GPE/Fixed Event is valid and enabled. 158 159 Root has permission to clear any of these counters. Eg. 160 # echo 0 > gpe11 161 162 All counters can be cleared by clearing the total "sci": 163 # echo 0 > sci 164 165 None of these counters has an effect on the function 166 of the system, they are simply statistics. 167 168 Besides this, user can also write specific strings to these files 169 to enable/disable/clear ACPI interrupts in user space, which can be 170 used to debug some ACPI interrupt storm issues. 171 172 Note that only writing to VALID GPE/Fixed Event is allowed, 173 i.e. user can only change the status of runtime GPE and 174 Fixed Event with event handler installed. 175 176 Let's take power button fixed event for example, please kill acpid 177 and other user space applications so that the machine won't shutdown 178 when pressing the power button. 179 # cat ff_pwr_btn 180 0 enabled 181 # press the power button for 3 times; 182 # cat ff_pwr_btn 183 3 enabled 184 # echo disable > ff_pwr_btn 185 # cat ff_pwr_btn 186 3 disabled 187 # press the power button for 3 times; 188 # cat ff_pwr_btn 189 3 disabled 190 # echo enable > ff_pwr_btn 191 # cat ff_pwr_btn 192 4 enabled 193 /* 194 * this is because the status bit is set even if the enable bit is cleared, 195 * and it triggers an ACPI fixed event when the enable bit is set again 196 */ 197 # press the power button for 3 times; 198 # cat ff_pwr_btn 199 7 enabled 200 # echo disable > ff_pwr_btn 201 # press the power button for 3 times; 202 # echo clear > ff_pwr_btn /* clear the status bit */ 203 # echo disable > ff_pwr_btn 204 # cat ff_pwr_btn 205 7 enabled 206 207