diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/Makefile | 5 | ||||
| -rw-r--r-- | Documentation/filesystems/Locking | 24 | ||||
| -rw-r--r-- | Documentation/input/bcm5974.txt | 65 | ||||
| -rw-r--r-- | Documentation/input/multi-touch-protocol.txt | 140 | ||||
| -rw-r--r-- | Documentation/isdn/00-INDEX | 17 | ||||
| -rw-r--r-- | Documentation/isdn/INTERFACE.CAPI | 213 | ||||
| -rw-r--r-- | Documentation/kernel-doc-nano-HOWTO.txt | 7 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 12 | ||||
| -rw-r--r-- | Documentation/lockdep-design.txt | 6 | ||||
| -rw-r--r-- | Documentation/sysctl/vm.txt | 4 |
10 files changed, 471 insertions, 22 deletions
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index 8918a32c6b3a..b1eb661e6302 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -143,7 +143,8 @@ quiet_cmd_db2pdf = PDF $@ $(call cmd,db2pdf) -main_idx = Documentation/DocBook/index.html +index = index.html +main_idx = Documentation/DocBook/$(index) build_main_index = rm -rf $(main_idx) && \ echo '<h1>Linux Kernel HTML Documentation</h1>' >> $(main_idx) && \ echo '<h2>Kernel Version: $(KERNELVERSION)</h2>' >> $(main_idx) && \ @@ -232,7 +233,7 @@ clean-files := $(DOCBOOKS) \ $(patsubst %.xml, %.pdf, $(DOCBOOKS)) \ $(patsubst %.xml, %.html, $(DOCBOOKS)) \ $(patsubst %.xml, %.9, $(DOCBOOKS)) \ - $(C-procfs-example) + $(C-procfs-example) $(index) clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 76efe5b71d7d..3120f8dd2c31 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -512,16 +512,24 @@ locking rules: BKL mmap_sem PageLocked(page) open: no yes close: no yes -fault: no yes -page_mkwrite: no yes no +fault: no yes can return with page locked +page_mkwrite: no yes can return with page locked access: no yes - ->page_mkwrite() is called when a previously read-only page is -about to become writeable. The file system is responsible for -protecting against truncate races. Once appropriate action has been -taking to lock out truncate, the page range should be verified to be -within i_size. The page mapping should also be checked that it is not -NULL. + ->fault() is called when a previously not present pte is about +to be faulted in. The filesystem must find and return the page associated +with the passed in "pgoff" in the vm_fault structure. If it is possible that +the page may be truncated and/or invalidated, then the filesystem must lock +the page, then ensure it is not already truncated (the page lock will block +subsequent truncate), and then return with VM_FAULT_LOCKED, and the page +locked. The VM will unlock the page. + + ->page_mkwrite() is called when a previously read-only pte is +about to become writeable. The filesystem again must ensure that there are +no truncate/invalidate races, and then return with the page locked. If +the page has been truncated, the filesystem should not look up a new page +like the ->fault() handler, but simply return with VM_FAULT_NOPAGE, which +will cause the VM to retry the fault. ->access() is called when get_user_pages() fails in acces_process_vm(), typically used to debug a process through diff --git a/Documentation/input/bcm5974.txt b/Documentation/input/bcm5974.txt new file mode 100644 index 000000000000..5e22dcf6d48d --- /dev/null +++ b/Documentation/input/bcm5974.txt @@ -0,0 +1,65 @@ +BCM5974 Driver (bcm5974) +------------------------ + Copyright (C) 2008-2009 Henrik Rydberg <rydberg@euromail.se> + +The USB initialization and package decoding was made by Scott Shawcroft as +part of the touchd user-space driver project: + Copyright (C) 2008 Scott Shawcroft (scott.shawcroft@gmail.com) + +The BCM5974 driver is based on the appletouch driver: + Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com) + Copyright (C) 2005 Johannes Berg (johannes@sipsolutions.net) + Copyright (C) 2005 Stelian Pop (stelian@popies.net) + Copyright (C) 2005 Frank Arnold (frank@scirocco-5v-turbo.de) + Copyright (C) 2005 Peter Osterlund (petero2@telia.com) + Copyright (C) 2005 Michael Hanselmann (linux-kernel@hansmi.ch) + Copyright (C) 2006 Nicolas Boichat (nicolas@boichat.ch) + +This driver adds support for the multi-touch trackpad on the new Apple +Macbook Air and Macbook Pro laptops. It replaces the appletouch driver on +those computers, and integrates well with the synaptics driver of the Xorg +system. + +Known to work on Macbook Air, Macbook Pro Penryn and the new unibody +Macbook 5 and Macbook Pro 5. + +Usage +----- + +The driver loads automatically for the supported usb device ids, and +becomes available both as an event device (/dev/input/event*) and as a +mouse via the mousedev driver (/dev/input/mice). + +USB Race +-------- + +The Apple multi-touch trackpads report both mouse and keyboard events via +different interfaces of the same usb device. This creates a race condition +with the HID driver, which, if not told otherwise, will find the standard +HID mouse and keyboard, and claim the whole device. To remedy, the usb +product id must be listed in the mouse_ignore list of the hid driver. + +Debug output +------------ + +To ease the development for new hardware version, verbose packet output can +be switched on with the debug kernel module parameter. The range [1-9] +yields different levels of verbosity. Example (as root): + +echo -n 9 > /sys/module/bcm5974/parameters/debug + +tail -f /var/log/debug + +echo -n 0 > /sys/module/bcm5974/parameters/debug + +Trivia +------ + +The driver was developed at the ubuntu forums in June 2008 [1], and now has +a more permanent home at bitmath.org [2]. + +Links +----- + +[1] http://ubuntuforums.org/showthread.php?t=840040 +[2] http://http://bitmath.org/code/ diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt new file mode 100644 index 000000000000..9f09557aea39 --- /dev/null +++ b/Documentation/input/multi-touch-protocol.txt @@ -0,0 +1,140 @@ +Multi-touch (MT) Protocol +------------------------- + Copyright (C) 2009 Henrik Rydberg <rydberg@euromail.se> + + +Introduction +------------ + +In order to utilize the full power of the new multi-touch devices, a way to +report detailed finger data to user space is needed. This document +describes the multi-touch (MT) protocol which allows kernel drivers to +report details for an arbitrary number of fingers. + + +Usage +----- + +Anonymous finger details are sent sequentially as separate packets of ABS +events. Only the ABS_MT events are recognized as part of a finger +packet. The end of a packet is marked by calling the input_mt_sync() +function, which generates a SYN_MT_REPORT event. The end of multi-touch +transfer is marked by calling the usual input_sync() function. + +A set of ABS_MT events with the desired properties is defined. The events +are divided into categories, to allow for partial implementation. The +minimum set consists of ABS_MT_TOUCH_MAJOR, ABS_MT_POSITION_X and +ABS_MT_POSITION_Y, which allows for multiple fingers to be tracked. If the +device supports it, the ABS_MT_WIDTH_MAJOR may be used to provide the size +of the approaching finger. Anisotropy and direction may be specified with +ABS_MT_TOUCH_MINOR, ABS_MT_WIDTH_MINOR and ABS_MT_ORIENTATION. Devices with +more granular information may specify general shapes as blobs, i.e., as a +sequence of rectangular shapes grouped together by an +ABS_MT_BLOB_ID. Finally, the ABS_MT_TOOL_TYPE may be used to specify +whether the touching tool is a finger or a pen or something else. + + +Event Semantics +--------------- + +The word "contact" is used to describe a tool which is in direct contact +with the surface. A finger, a pen or a rubber all classify as contacts. + +ABS_MT_TOUCH_MAJOR + +The length of the major axis of the contact. The length should be given in +surface units. If the surface has an X times Y resolution, the largest +possible value of ABS_MT_TOUCH_MAJOR is sqrt(X^2 + Y^2), the diagonal. + +ABS_MT_TOUCH_MINOR + +The length, in surface units, of the minor axis of the contact. If the +contact is circular, this event can be omitted. + +ABS_MT_WIDTH_MAJOR + +The length, in surface units, of the major axis of the approaching +tool. This should be understood as the size of the tool itself. The +orientation of the contact and the approaching tool are assumed to be the +same. + +ABS_MT_WIDTH_MINOR + +The length, in surface units, of the minor axis of the approaching +tool. Omit if circular. + +The above four values can be used to derive additional information about +the contact. The ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR approximates +the notion of pressure. The fingers of the hand and the palm all have +different characteristic widths [1]. + +ABS_MT_ORIENTATION + +The orientation of the ellipse. The value should describe half a revolution +clockwise around the touch center. The scale of the value is arbitrary, but +zero should be returned for an ellipse aligned along the Y axis of the +surface. As an example, an index finger placed straight onto the axis could +return zero orientation, something negative when twisted to the left, and +something positive when twisted to the right. This value can be omitted if +the touching object is circular, or if the information is not available in +the kernel driver. + +ABS_MT_POSITION_X + +The surface X coordinate of the center of the touching ellipse. + +ABS_MT_POSITION_Y + +The surface Y coordinate of the center of the touching ellipse. + +ABS_MT_TOOL_TYPE + +The type of approaching tool. A lot of kernel drivers cannot distinguish +between different tool types, such as a finger or a pen. In such cases, the +event should be omitted. The protocol currently supports MT_TOOL_FINGER and +MT_TOOL_PEN [2]. + +ABS_MT_BLOB_ID + +The BLOB_ID groups several packets together into one arbitrarily shaped +contact. This is a low-level anonymous grouping, and should not be confused +with the high-level contactID, explained below. Most kernel drivers will +not have this capability, and can safely omit the event. + + +Finger Tracking +--------------- + +The kernel driver should generate an arbitrary enumeration of the set of +anonymous contacts currently on the surface. The order in which the packets +appear in the event stream is not important. + +The process of finger tracking, i.e., to assign a unique contactID to each +initiated contact on the surface, is left to user space; preferably the +multi-touch X driver [3]. In that driver, the contactID stays the same and +unique until the contact vanishes (when the finger leaves the surface). The +problem of assigning a set of anonymous fingers to a set of identified +fingers is a euclidian bipartite matching problem at each event update, and +relies on a sufficiently rapid update rate. + +Notes +----- + +In order to stay compatible with existing applications, the data +reported in a finger packet must not be recognized as single-touch +events. In addition, all finger data must bypass input filtering, +since subsequent events of the same type refer to different fingers. + +The first kernel driver to utilize the MT protocol is the bcm5974 driver, +where examples can be found. + +[1] With the extension ABS_MT_APPROACH_X and ABS_MT_APPROACH_Y, the +difference between the contact position and the approaching tool position +could be used to derive tilt. +[2] The list can of course be extended. +[3] The multi-touch X driver is currently in the prototyping stage. At the +time of writing (April 2009), the MT protocol is not yet merged, and the +prototype implements finger matching, basic mouse support and two-finger +scrolling. The project aims at improving the quality of current multi-touch +functionality available in the synaptics X driver, and in addition +implement more advanced gestures. diff --git a/Documentation/isdn/00-INDEX b/Documentation/isdn/00-INDEX index 9fee5f2e5c62..5a2d69989a8c 100644 --- a/Documentation/isdn/00-INDEX +++ b/Documentation/isdn/00-INDEX @@ -2,8 +2,14 @@ - this file (info on ISDN implementation for Linux) CREDITS - list of the kind folks that brought you this stuff. +HiSax.cert + - information about the ITU approval certification of the HiSax driver. INTERFACE - - description of Linklevel and Hardwarelevel ISDN interface. + - description of isdn4linux Link Level and Hardware Level interfaces. +INTERFACE.fax + - description of the fax subinterface of isdn4linux. +INTERFACE.CAPI + - description of kernel CAPI Link Level to Hardware Level interface. README - general info on what you need and what to do for Linux ISDN. README.FAQ @@ -12,6 +18,8 @@ README.audio - info for running audio over ISDN. README.fax - info for using Fax over ISDN. +README.gigaset + - info on the drivers for Siemens Gigaset ISDN adapters. README.icn - info on the ICN-ISDN-card and its driver. README.HiSax @@ -37,7 +45,8 @@ README.diversion README.sc - info on driver for Spellcaster cards. README.x25 - _ info for running X.25 over ISDN. + - info for running X.25 over ISDN. README.hysdn - - info on driver for Hypercope active HYSDN cards - + - info on driver for Hypercope active HYSDN cards +README.mISDN + - info on the Modular ISDN subsystem (mISDN). diff --git a/Documentation/isdn/INTERFACE.CAPI b/Documentation/isdn/INTERFACE.CAPI new file mode 100644 index 000000000000..786d619b36e5 --- /dev/null +++ b/Documentation/isdn/INTERFACE.CAPI @@ -0,0 +1,213 @@ +Kernel CAPI Interface to Hardware Drivers +----------------------------------------- + +1. Overview + +From the CAPI 2.0 specification: +COMMON-ISDN-API (CAPI) is an application programming interface standard used +to access ISDN equipment connected to basic rate interfaces (BRI) and primary +rate interfaces (PRI). + +Kernel CAPI operates as a dispatching layer between CAPI applications and CAPI +hardware drivers. Hardware drivers register ISDN devices (controllers, in CAPI +lingo) with Kernel CAPI to indicate their readiness to provide their service +to CAPI applications. CAPI applications also register with Kernel CAPI, +requesting association with a CAPI device. Kernel CAPI then dispatches the +application registration to an available device, forwarding it to the +corresponding hardware driver. Kernel CAPI then forwards CAPI messages in both +directions between the application and the hardware driver. + +Format and semantics of CAPI messages are specified in the CAPI 2.0 standard. +This standard is freely available from http://www.capi.org. + + +2. Driver and Device Registration + +CAPI drivers optionally register themselves with Kernel CAPI by calling the +Kernel CAPI function register_capi_driver() with a pointer to a struct +capi_driver. This structure must be filled with the name and revision of the +driver, and optionally a pointer to a callback function, add_card(). The +registration can be revoked by calling the function unregister_capi_driver() +with a pointer to the same struct capi_driver. + +CAPI drivers must register each of the ISDN devices they control with Kernel +CAPI by calling the Kernel CAPI function attach_capi_ctr() with a pointer to a +struct capi_ctr before they can be used. This structure must be filled with +the names of the driver and controller, and a number of callback function +pointers which are subsequently used by Kernel CAPI for communicating with the +driver. The registration can be revoked by calling the function +detach_capi_ctr() with a pointer to the same struct capi_ctr. + +Before the device can be actually used, the driver must fill in the device +information fields 'manu', 'version', 'profile' and 'serial' in the capi_ctr +structure of the device, and signal its readiness by calling capi_ctr_ready(). +From then on, Kernel CAPI may call the registered callback functions for the +device. + +If the device becomes unusable for any reason (shutdown, disconnect ...), the +driver has to call capi_ctr_reseted(). This will prevent further calls to the +callback functions by Kernel CAPI. + + +3. Application Registration and Communication + +Kernel CAPI forwards registration requests from applications (calls to CAPI +operation CAPI_REGISTER) to an appropriate hardware driver by calling its +register_appl() callback function. A unique Application ID (ApplID, u16) is +allocated by Kernel CAPI and passed to register_appl() along with the +parameter structure provided by the application. This is analogous to the +open() operation on regular files or character devices. + +After a successful return from register_appl(), CAPI messages from the +application may be passed to the driver for the device via calls to the +send_message() callback function. The CAPI message to send is stored in the +data portion of an skb. Conversely, the driver may call Kernel CAPI's +capi_ctr_handle_message() function to pass a received CAPI message to Kernel +CAPI for forwarding to an application, specifying its ApplID. + +Deregistration requests (CAPI operation CAPI_RELEASE) from applications are +forwarded as calls to the release_appl() callback function, passing the same +ApplID as with register_appl(). After return from release_appl(), no CAPI +messages for that application may be passed to or from the device anymore. + + +4. Data Structures + +4.1 struct capi_driver + +This structure describes a Kernel CAPI driver itself. It is used in the +register_capi_driver() and unregister_capi_driver() functions, and contains +the following non-private fields, all to be set by the driver before calling +register_capi_driver(): + +char name[32] + the name of the driver, as a zero-terminated ASCII string +char revision[32] + the revision number of the driver, as a zero-terminated ASCII string +int (*add_card)(struct capi_driver *driver, capicardparams *data) + a callback function pointer (may be NULL) + + +4.2 struct capi_ctr + +This structure describes an ISDN device (controller) handled by a Kernel CAPI +driver. After registration via the attach_capi_ctr() function it is passed to +all controller specific lower layer interface and callback functions to +identify the controller to operate on. + +It contains the following non-private fields: + +- to be set by the driver before calling attach_capi_ctr(): + +struct module *owner + pointer to the driver module owning the device + +void *driverdata + an opaque pointer to driver specific data, not touched by Kernel CAPI + +char name[32] + the name of the controller, as a zero-terminated ASCII string + +char *driver_name + the name of the driver, as a zero-terminated ASCII string + +int (*load_firmware)(struct capi_ctr *ctrlr, capiloaddata *ldata) + (optional) pointer to a callback function for sending firmware and + configuration data to the device + +void (*reset_ctr)(struct capi_ctr *ctrlr) + pointer to a callback function for performing a reset on the device, + releasing all registered applications + +void (*register_appl)(struct capi_ctr *ctrlr, u16 applid, + capi_register_params *rparam) +void (*release_appl)(struct capi_ctr *ctrlr, u16 applid) + pointers to callback functions for registration and deregistration of + applications with the device + +u16 (*send_message)(struct capi_ctr *ctrlr, struct sk_buff *skb) + pointer to a callback function for sending a CAPI message to the + device + +char *(*procinfo)(struct capi_ctr *ctrlr) + pointer to a callback function returning the entry for the device in + the CAPI controller info table, /proc/capi/controller + +read_proc_t *ctr_read_proc + pointer to the read_proc callback function for the device's proc file + system entry, /proc/capi/controllers/<n>; will be called with a + pointer to the device's capi_ctr structure as the last (data) argument + +- to be filled in before calling capi_ctr_ready(): + +u8 manu[CAPI_MANUFACTURER_LEN] + value to return for CAPI_GET_MANUFACTURER + +capi_version version + value to return for CAPI_GET_VERSION + +capi_profile profile + value to return for CAPI_GET_PROFILE + +u8 serial[CAPI_SERIAL_LEN] + value to return for CAPI_GET_SERIAL + + +5. Lower Layer Interface Functions + +(declared in <linux/isdn/capilli.h>) + +void register_capi_driver(struct capi_driver *drvr) +void unregister_capi_driver(struct capi_driver *drvr) + register/unregister a driver with Kernel CAPI + +int attach_capi_ctr(struct capi_ctr *ctrlr) +int detach_capi_ctr(struct capi_ctr *ctrlr) + register/unregister a device (controller) with Kernel CAPI + +void capi_ctr_ready(struct capi_ctr *ctrlr) +void capi_ctr_reseted(struct capi_ctr *ctrlr) + signal controller ready/not ready + +void capi_ctr_suspend_output(struct capi_ctr *ctrlr) +void capi_ctr_resume_output(struct capi_ctr *ctrlr) + signal suspend/resume + +void capi_ctr_handle_message(struct capi_ctr * ctrlr, u16 applid, + struct sk_buff *skb) + pass a received CAPI message to Kernel CAPI + for forwarding to the specified application + + +6. Helper Functions and Macros + +Library functions (from <linux/isdn/capilli.h>): + +void capilib_new_ncci(struct list_head *head, u16 applid, + u32 ncci, u32 winsize) +void capilib_free_ncci(struct list_head *head, u16 applid, u32 ncci) +void capilib_release_appl(struct list_head *head, u16 applid) +void capilib_release(struct list_head *head) +void capilib_data_b3_conf(struct list_head *head, u16 applid, + u32 ncci, u16 msgid) +u16 capilib_data_b3_req(struct list_head *head, u16 applid, + u32 ncci, u16 msgid) + + +Macros to extract/set element values from/in a CAPI message header +(from <linux/isdn/capiutil.h>): + +Get Macro Set Macro Element (Type) + +CAPIMSG_LEN(m) CAPIMSG_SETLEN(m, len) Total Length (u16) +CAPIMSG_APPID(m) CAPIMSG_SETAPPID(m, applid) ApplID (u16) +CAPIMSG_COMMAND(m) CAPIMSG_SETCOMMAND(m,cmd) Command (u8) +CAPIMSG_SUBCOMMAND(m) CAPIMSG_SETSUBCOMMAND(m, cmd) Subcommand (u8) +CAPIMSG_CMD(m) - Command*256 + + Subcommand (u16) +CAPIMSG_MSGID(m) CAPIMSG_SETMSGID(m, msgid) Message Number (u16) + +CAPIMSG_CONTROL(m) CAPIMSG_SETCONTROL(m, contr) Controller/PLCI/NCCI + (u32) +CAPIMSG_DATALEN(m) CAPIMSG_SETDATALEN(m, len) Data Length (u16) + diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 026ec7d57384..4d04572b6549 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -269,7 +269,10 @@ Use the argument mechanism to document members or constants. Inside a struct description, you can use the "private:" and "public:" comment tags. Structure fields that are inside a "private:" area -are not listed in the generated output documentation. +are not listed in the generated output documentation. The "private:" +and "public:" tags must begin immediately following a "/*" comment +marker. They may optionally include comments between the ":" and the +ending "*/" marker. Example: @@ -283,7 +286,7 @@ Example: struct my_struct { int a; int b; -/* private: */ +/* private: internal use only */ int c; }; diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 90b3924071b6..e87bdbfbcc75 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -17,6 +17,12 @@ are specified on the kernel command line with the module name plus usbcore.blinkenlights=1 +Hyphens (dashes) and underscores are equivalent in parameter names, so + log_buf_len=1M print-fatal-signals=1 +can also be entered as + log-buf-len=1M print_fatal_signals=1 + + This document may not be entirely up to date and comprehensive. The command "modinfo -p ${modulename}" shows a current list of all parameters of a loadable module. Loadable modules, after being loaded into the running kernel, also @@ -345,7 +351,7 @@ and is between 256 and 4096 characters. It is defined in the file not play well with APC CPU idle - disable it if you have APC and your system crashes randomly. - apic= [APIC,i386] Advanced Programmable Interrupt Controller + apic= [APIC,X86-32] Advanced Programmable Interrupt Controller Change the output verbosity whilst booting Format: { quiet (default) | verbose | debug } Change the amount of debugging information output @@ -702,7 +708,7 @@ and is between 256 and 4096 characters. It is defined in the file to discrete, to make X server driver able to add WB entry later. This parameter enables that. - enable_timer_pin_1 [i386,x86-64] + enable_timer_pin_1 [X86] Enable PIN 1 of APIC timer Can be useful to work around chipset bugs (in particular on some ATI chipsets). @@ -775,7 +781,7 @@ and is between 256 and 4096 characters. It is defined in the file hashdist= [KNL,NUMA] Large hashes allocated during boot are distributed across NUMA nodes. Defaults on - for IA-64, off otherwise. + for 64bit NUMA, off otherwise. Format: 0 | 1 (for off | on) hcl= [IA-64] SGI's Hardware Graph compatibility layer diff --git a/Documentation/lockdep-design.txt b/Documentation/lockdep-design.txt index 938ea22f2cc0..e20d913d5914 100644 --- a/Documentation/lockdep-design.txt +++ b/Documentation/lockdep-design.txt @@ -54,9 +54,9 @@ locking error messages, inside curlies. A contrived example: The bit position indicates STATE, STATE-read, for each of the states listed above, and the character displayed in each indicates: - '.' acquired while irqs disabled - '+' acquired in irq context - '-' acquired with irqs enabled + '.' acquired while irqs disabled and not in irq context + '-' acquired in irq context + '+' acquired with irqs enabled '?' acquired in irq context with irqs enabled. Unused mutexes cannot be part of the cause of an error. diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 97c4b3284329..b716d33912d8 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -90,6 +90,10 @@ will itself start writeback. If dirty_bytes is written, dirty_ratio becomes a function of its value (dirty_bytes / the amount of dirtyable system memory). +Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any +value lower than this limit will be ignored and the old configuration will be +retained. + ============================================================== dirty_expire_centisecs |
