diff options
Diffstat (limited to 'Documentation')
35 files changed, 1995 insertions, 195 deletions
diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl index 7f5f218015f..08ff908aa7a 100644 --- a/Documentation/DocBook/debugobjects.tmpl +++ b/Documentation/DocBook/debugobjects.tmpl @@ -106,7 +106,7 @@ number of errors are printk'ed including a full stack trace. </para> <para> - The statistics are available via debugfs/debug_objects/stats. + The statistics are available via /sys/kernel/debug/debug_objects/stats. They provide information about the number of warnings and the number of successful fixups along with information about the usage of the internal tracking objects and the state of the diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c index 7ea231172c8..aa73e72fd79 100644 --- a/Documentation/accounting/getdelays.c +++ b/Documentation/accounting/getdelays.c @@ -246,7 +246,8 @@ void print_ioacct(struct taskstats *t) int main(int argc, char *argv[]) { - int c, rc, rep_len, aggr_len, len2, cmd_type; + int c, rc, rep_len, aggr_len, len2; + int cmd_type = TASKSTATS_CMD_ATTR_UNSPEC; __u16 id; __u32 mypid; diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt index 4ef24501045..396bec3b74e 100644 --- a/Documentation/atomic_ops.txt +++ b/Documentation/atomic_ops.txt @@ -229,10 +229,10 @@ kernel. It is the use of atomic counters to implement reference counting, and it works such that once the counter falls to zero it can be guaranteed that no other entity can be accessing the object: -static void obj_list_add(struct obj *obj) +static void obj_list_add(struct obj *obj, struct list_head *head) { obj->active = 1; - list_add(&obj->list); + list_add(&obj->list, head); } static void obj_list_del(struct obj *obj) diff --git a/Documentation/cdrom/packet-writing.txt b/Documentation/cdrom/packet-writing.txt index cf1f8126991..1c407778c8b 100644 --- a/Documentation/cdrom/packet-writing.txt +++ b/Documentation/cdrom/packet-writing.txt @@ -117,7 +117,7 @@ Using the pktcdvd debugfs interface To read pktcdvd device infos in human readable form, do: - # cat /debug/pktcdvd/pktcdvd[0-7]/info + # cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info For a description of the debugfs interface look into the file: diff --git a/Documentation/driver-model/device.txt b/Documentation/driver-model/device.txt index a7cbfff40d0..a124f3126b0 100644 --- a/Documentation/driver-model/device.txt +++ b/Documentation/driver-model/device.txt @@ -162,3 +162,35 @@ device_remove_file(dev,&dev_attr_power); The file name will be 'power' with a mode of 0644 (-rw-r--r--). +Word of warning: While the kernel allows device_create_file() and +device_remove_file() to be called on a device at any time, userspace has +strict expectations on when attributes get created. When a new device is +registered in the kernel, a uevent is generated to notify userspace (like +udev) that a new device is available. If attributes are added after the +device is registered, then userspace won't get notified and userspace will +not know about the new attributes. + +This is important for device driver that need to publish additional +attributes for a device at driver probe time. If the device driver simply +calls device_create_file() on the device structure passed to it, then +userspace will never be notified of the new attributes. Instead, it should +probably use class_create() and class->dev_attrs to set up a list of +desired attributes in the modules_init function, and then in the .probe() +hook, and then use device_create() to create a new device as a child +of the probed device. The new device will generate a new uevent and +properly advertise the new attributes to userspace. + +For example, if a driver wanted to add the following attributes: +struct device_attribute mydriver_attribs[] = { + __ATTR(port_count, 0444, port_count_show), + __ATTR(serial_number, 0444, serial_number_show), + NULL +}; + +Then in the module init function is would do: + mydriver_class = class_create(THIS_MODULE, "my_attrs"); + mydriver_class.dev_attr = mydriver_attribs; + +And assuming 'dev' is the struct device passed into the probe hook, the driver +probe function would do something like: + create_device(&mydriver_class, dev, chrdev, &private_data, "my_name"); diff --git a/Documentation/dvb/get_dvb_firmware b/Documentation/dvb/get_dvb_firmware index 2f21ecd4c20..a52adfc9a57 100644 --- a/Documentation/dvb/get_dvb_firmware +++ b/Documentation/dvb/get_dvb_firmware @@ -112,7 +112,7 @@ sub tda10045 { sub tda10046 { my $sourcefile = "TT_PCI_2.19h_28_11_2006.zip"; - my $url = "http://technotrend-online.com/download/software/219/$sourcefile"; + my $url = "http://www.tt-download.com/download/updates/219/$sourcefile"; my $hash = "6a7e1e2f2644b162ff0502367553c72d"; my $outfile = "dvb-fe-tda10046.fw"; my $tmpdir = tempdir(DIR => "/tmp", CLEANUP => 1); @@ -129,8 +129,8 @@ sub tda10046 { } sub tda10046lifeview { - my $sourcefile = "Drv_2.11.02.zip"; - my $url = "http://www.lifeview.com.tw/drivers/pci_card/FlyDVB-T/$sourcefile"; + my $sourcefile = "7%5Cdrv_2.11.02.zip"; + my $url = "http://www.lifeview.hk/dbimages/document/$sourcefile"; my $hash = "1ea24dee4eea8fe971686981f34fd2e0"; my $outfile = "dvb-fe-tda10046.fw"; my $tmpdir = tempdir(DIR => "/tmp", CLEANUP => 1); @@ -317,7 +317,7 @@ sub nxt2002 { sub nxt2004 { my $sourcefile = "AVerTVHD_MCE_A180_Drv_v1.2.2.16.zip"; - my $url = "http://www.aver.com/support/Drivers/$sourcefile"; + my $url = "http://www.avermedia-usa.com/support/Drivers/$sourcefile"; my $hash = "111cb885b1e009188346d72acfed024c"; my $outfile = "dvb-fe-nxt2004.fw"; my $tmpdir = tempdir(DIR => "/tmp", CLEANUP => 1); diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt index 4bc374a1434..07930564079 100644 --- a/Documentation/fault-injection/fault-injection.txt +++ b/Documentation/fault-injection/fault-injection.txt @@ -29,16 +29,16 @@ o debugfs entries fault-inject-debugfs kernel module provides some debugfs entries for runtime configuration of fault-injection capabilities. -- /debug/fail*/probability: +- /sys/kernel/debug/fail*/probability: likelihood of failure injection, in percent. Format: <percent> Note that one-failure-per-hundred is a very high error rate for some testcases. Consider setting probability=100 and configure - /debug/fail*/interval for such testcases. + /sys/kernel/debug/fail*/interval for such testcases. -- /debug/fail*/interval: +- /sys/kernel/debug/fail*/interval: specifies the interval between failures, for calls to should_fail() that pass all the other tests. @@ -46,18 +46,18 @@ configuration of fault-injection capabilities. Note that if you enable this, by setting interval>1, you will probably want to set probability=100. -- /debug/fail*/times: +- /sys/kernel/debug/fail*/times: specifies how many times failures may happen at most. A value of -1 means "no limit". -- /debug/fail*/space: +- /sys/kernel/debug/fail*/space: specifies an initial resource "budget", decremented by "size" on each call to should_fail(,size). Failure injection is suppressed until "space" reaches zero. -- /debug/fail*/verbose +- /sys/kernel/debug/fail*/verbose Format: { 0 | 1 | 2 } specifies the verbosity of the messages when failure is @@ -65,17 +65,17 @@ configuration of fault-injection capabilities. log line per failure; '2' will print a call trace too -- useful to debug the problems revealed by fault injection. -- /debug/fail*/task-filter: +- /sys/kernel/debug/fail*/task-filter: Format: { 'Y' | 'N' } A value of 'N' disables filtering by process (default). Any positive value limits failures to only processes indicated by /proc/<pid>/make-it-fail==1. -- /debug/fail*/require-start: -- /debug/fail*/require-end: -- /debug/fail*/reject-start: -- /debug/fail*/reject-end: +- /sys/kernel/debug/fail*/require-start: +- /sys/kernel/debug/fail*/require-end: +- /sys/kernel/debug/fail*/reject-start: +- /sys/kernel/debug/fail*/reject-end: specifies the range of virtual addresses tested during stacktrace walking. Failure is injected only if some caller @@ -84,26 +84,26 @@ configuration of fault-injection capabilities. Default required range is [0,ULONG_MAX) (whole of virtual address space). Default rejected range is [0,0). -- /debug/fail*/stacktrace-depth: +- /sys/kernel/debug/fail*/stacktrace-depth: specifies the maximum stacktrace depth walked during search for a caller within [require-start,require-end) OR [reject-start,reject-end). -- /debug/fail_page_alloc/ignore-gfp-highmem: +- /sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem: Format: { 'Y' | 'N' } default is 'N', setting it to 'Y' won't inject failures into highmem/user allocations. -- /debug/failslab/ignore-gfp-wait: -- /debug/fail_page_alloc/ignore-gfp-wait: +- /sys/kernel/debug/failslab/ignore-gfp-wait: +- /sys/kernel/debug/fail_page_alloc/ignore-gfp-wait: Format: { 'Y' | 'N' } default is 'N', setting it to 'Y' will inject failures only into non-sleep allocations (GFP_ATOMIC allocations). -- /debug/fail_page_alloc/min-order: +- /sys/kernel/debug/fail_page_alloc/min-order: specifies the minimum page allocation order to be injected failures. @@ -166,13 +166,13 @@ o Inject slab allocation failures into module init/exit code #!/bin/bash FAILTYPE=failslab -echo Y > /debug/$FAILTYPE/task-filter -echo 10 > /debug/$FAILTYPE/probability -echo 100 > /debug/$FAILTYPE/interval -echo -1 > /debug/$FAILTYPE/times -echo 0 > /debug/$FAILTYPE/space -echo 2 > /debug/$FAILTYPE/verbose -echo 1 > /debug/$FAILTYPE/ignore-gfp-wait +echo Y > /sys/kernel/debug/$FAILTYPE/task-filter +echo 10 > /sys/kernel/debug/$FAILTYPE/probability +echo 100 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 2 > /sys/kernel/debug/$FAILTYPE/verbose +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait faulty_system() { @@ -217,20 +217,20 @@ then exit 1 fi -cat /sys/module/$module/sections/.text > /debug/$FAILTYPE/require-start -cat /sys/module/$module/sections/.data > /debug/$FAILTYPE/require-end +cat /sys/module/$module/sections/.text > /sys/kernel/debug/$FAILTYPE/require-start +cat /sys/module/$module/sections/.data > /sys/kernel/debug/$FAILTYPE/require-end -echo N > /debug/$FAILTYPE/task-filter -echo 10 > /debug/$FAILTYPE/probability -echo 100 > /debug/$FAILTYPE/interval -echo -1 > /debug/$FAILTYPE/times -echo 0 > /debug/$FAILTYPE/space -echo 2 > /debug/$FAILTYPE/verbose -echo 1 > /debug/$FAILTYPE/ignore-gfp-wait -echo 1 > /debug/$FAILTYPE/ignore-gfp-highmem -echo 10 > /debug/$FAILTYPE/stacktrace-depth +echo N > /sys/kernel/debug/$FAILTYPE/task-filter +echo 10 > /sys/kernel/debug/$FAILTYPE/probability +echo 100 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 2 > /sys/kernel/debug/$FAILTYPE/verbose +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait +echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-highmem +echo 10 > /sys/kernel/debug/$FAILTYPE/stacktrace-depth -trap "echo 0 > /debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT +trap "echo 0 > /sys/kernel/debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT echo "Injecting errors into the module $module... (interrupt to stop)" sleep 1000000 diff --git a/Documentation/fb/vesafb.txt b/Documentation/fb/vesafb.txt index ee277dd204b..950d5a658cb 100644 --- a/Documentation/fb/vesafb.txt +++ b/Documentation/fb/vesafb.txt @@ -95,7 +95,7 @@ There is no way to change the vesafb video mode and/or timings after booting linux. If you are not happy with the 60 Hz refresh rate, you have these options: - * configure and load the DOS-Tools for your the graphics board (if + * configure and load the DOS-Tools for the graphics board (if available) and boot linux with loadlin. * use a native driver (matroxfb/atyfb) instead if vesafb. If none is available, write a new one! diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index cd8717a3627..ebff3c10a07 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1003,11 +1003,13 @@ CHAPTER 3: PER-PROCESS PARAMETERS 3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score ------------------------------------------------------ -This file can be used to adjust the score used to select which processes -should be killed in an out-of-memory situation. Giving it a high score will -increase the likelihood of this process being killed by the oom-killer. Valid -values are in the range -16 to +15, plus the special value -17, which disables -oom-killing altogether for this process. +This file can be used to adjust the score used to select which processes should +be killed in an out-of-memory situation. The oom_adj value is a characteristic +of the task's mm, so all threads that share an mm with pid will have the same +oom_adj value. A high value will increase the likelihood of this process being +killed by the oom-killer. Valid values are in the range -16 to +15 as +explained below and a special value of -17, which disables oom-killing +altogether for threads sharing pid's mm. The process to be killed in an out-of-memory situation is selected among all others based on its badness score. This value equals the original memory size of the process @@ -1021,6 +1023,9 @@ the parent's score if they do not share the same memory. Thus forking servers are the prime candidates to be killed. Having only one 'hungry' child will make parent less preferable than the child. +/proc/<pid>/oom_adj cannot be changed for kthreads since they are immune from +oom-killing already. + /proc/<pid>/oom_score shows process' current badness score. The following heuristics are then applied: diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index 5147be5e13c..b58b84b50fa 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -132,6 +132,11 @@ rodir -- FAT has the ATTR_RO (read-only) attribute. On Windows, If you want to use ATTR_RO as read-only flag even for the directory, set this option. +errors=panic|continue|remount-ro + -- specify FAT behavior on critical errors: panic, continue + without doing anything or remount the partition in + read-only mode (default behavior). + <bool>: 0,1,yes,no,true,false TODO diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README index c3480aa66ba..7eceaff63f5 100644 --- a/Documentation/firmware_class/README +++ b/Documentation/firmware_class/README @@ -77,7 +77,8 @@ seconds for the whole load operation. - request_firmware_nowait() is also provided for convenience in - non-user contexts. + user contexts to request firmware asynchronously, but can't be called + in atomic contexts. about in-kernel persistence: diff --git a/Documentation/hwmon/f71882fg b/Documentation/hwmon/f71882fg index a8321267b5b..bee4c30bc1e 100644 --- a/Documentation/hwmon/f71882fg +++ b/Documentation/hwmon/f71882fg @@ -2,14 +2,18 @@ Kernel driver f71882fg ====================== Supported chips: - * Fintek F71882FG and F71883FG - Prefix: 'f71882fg' + * Fintek F71858FG + Prefix: 'f71858fg' Addresses scanned: none, address read from Super I/O config space Datasheet: Available from the Fintek website * Fintek F71862FG and F71863FG Prefix: 'f71862fg' Addresses scanned: none, address read from Super I/O config space Datasheet: Available from the Fintek website + * Fintek F71882FG and F71883FG + Prefix: 'f71882fg' + Addresses scanned: none, address read from Super I/O config space + Datasheet: Available from the Fintek website * Fintek F8000 Prefix: 'f8000' Addresses scanned: none, address read from Super I/O config space @@ -66,13 +70,13 @@ printed when loading the driver. Three different fan control modes are supported; the mode number is written to the pwm#_enable file. Note that not all modes are supported on all -chips, and some modes may only be available in RPM / PWM mode on the F8000. +chips, and some modes may only be available in RPM / PWM mode. Writing an unsupported mode will result in an invalid parameter error. * 1: Manual mode You ask for a specific PWM duty cycle / DC voltage or a specific % of fan#_full_speed by writing to the pwm# file. This mode is only - available on the F8000 if the fan channel is in RPM mode. + available on the F71858FG / F8000 if the fan channel is in RPM mode. * 2: Normal auto mode You can define a number of temperature/fan speed trip points, which % the diff --git a/Documentation/hwmon/ibmaem b/Documentation/hwmon/ibmaem index e98bdfea346..1e0d59e000b 100644 --- a/Documentation/hwmon/ibmaem +++ b/Documentation/hwmon/ibmaem @@ -7,7 +7,7 @@ henceforth as AEM. Supported systems: * Any recent IBM System X server with AEM support. This includes the x3350, x3550, x3650, x3655, x3755, x3850 M2, - x3950 M2, and certain HS2x/LS2x/QS2x blades. The IPMI host interface + x3950 M2, and certain HC10/HS2x/LS2x/QS2x blades. The IPMI host interface driver ("ipmi-si") needs to be loaded for this driver to do anything. Prefix: 'ibmaem' Datasheet: Not available diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface index 004ee161721..dcbd502c879 100644 --- a/Documentation/hwmon/sysfs-interface +++ b/Documentation/hwmon/sysfs-interface @@ -70,6 +70,7 @@ are interpreted as 0! For more on how written strings are interpreted see the [0-*] denotes any positive number starting from 0 [1-*] denotes any positive number starting from 1 RO read only value +WO write only value RW read/write value Read/write values may be read-only for some chips, depending on the @@ -295,6 +296,24 @@ temp[1-*]_label Suggested temperature channel label. user-space. RO +temp[1-*]_lowest + Historical minimum temperature + Unit: millidegree Celsius + RO + +temp[1-*]_highest + Historical maximum temperature + Unit: millidegree Celsius + RO + +temp[1-*]_reset_history + Reset temp_lowest and temp_highest + WO + +temp_reset_history + Reset temp_lowest and temp_highest for all sensors + WO + Some chips measure temperature using external thermistors and an ADC, and report the temperature measurement as a voltage. Converting this voltage back to a temperature (or the other way around for limits) requires diff --git a/Documentation/hwmon/tmp401 b/Documentation/hwmon/tmp401 new file mode 100644 index 00000000000..9fc44724921 --- /dev/null +++ b/Documentation/hwmon/tmp401 @@ -0,0 +1,42 @@ +Kernel driver tmp401 +==================== + +Supported chips: + * Texas Instruments TMP401 + Prefix: 'tmp401' + Addresses scanned: I2C 0x4c + Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp401.html + * Texas Instruments TMP411 + Prefix: 'tmp411' + Addresses scanned: I2C 0x4c + Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp411.html + +Authors: + Hans de Goede <hdegoede@redhat.com> + Andre Prendel <andre.prendel@gmx.de> + +Description +----------- + +This driver implements support for Texas Instruments TMP401 and +TMP411 chips. These chips implements one remote and one local +temperature sensor. Temperature is measured in degrees +Celsius. Resolution of the remote sensor is 0.0625 degree. Local +sensor resolution can be set to 0.5, 0.25, 0.125 or 0.0625 degree (not +supported by the driver so far, so using the default resolution of 0.5 +degree). + +The driver provides the common sysfs-interface for temperatures (see +/Documentation/hwmon/sysfs-interface under Temperatures). + +The TMP411 chip is compatible with TMP401. It provides some additional +features. + +* Minimum and Maximum temperature measured since power-on, chip-reset + + Exported via sysfs attributes tempX_lowest and tempX_highest. + +* Reset of historical minimum/maximum temperature measurements + + Exported via sysfs attribute temp_reset_history. Writing 1 to this + file triggers a reset. diff --git a/Documentation/hwmon/w83627ehf b/Documentation/hwmon/w83627ehf index b6eb59384bb..02b74899eda 100644 --- a/Documentation/hwmon/w83627ehf +++ b/Documentation/hwmon/w83627ehf @@ -12,6 +12,10 @@ Supported chips: Addresses scanned: ISA address retrieved from Super I/O registers Datasheet: http://www.nuvoton.com.tw/NR/rdonlyres/7885623D-A487-4CF9-A47F-30C5F73D6FE6/0/W83627DHG.pdf + * Winbond W83627DHG-P + Prefix: 'w83627dhg' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: not available * Winbond W83667HG Prefix: 'w83667hg' Addresses scanned: ISA address retrieved from Super I/O registers @@ -28,8 +32,8 @@ Description ----------- This driver implements support for the Winbond W83627EHF, W83627EHG, -W83627DHG and W83667HG super I/O chips. We will refer to them collectively -as Winbond chips. +W83627DHG, W83627DHG-P and W83667HG super I/O chips. We will refer to them +collectively as Winbond chips. The chips implement three temperature sensors, five fan rotation speed sensors, ten analog voltage sensors (only nine for the 627DHG), one @@ -135,3 +139,6 @@ done in the driver for all register addresses. The DHG also supports PECI, where the DHG queries Intel CPU temperatures, and the ICH8 southbridge gets that data via PECI from the DHG, so that the southbridge drives the fans. And the DHG supports SST, a one-wire serial bus. + +The DHG-P has an additional automatic fan speed control mode named Smart Fan +(TM) III+. This mode is not yet supported by the driver. diff --git a/Documentation/i2c/busses/i2c-viapro b/Documentation/i2c/busses/i2c-viapro index 22efedf60c8..2e758b0e945 100644 --- a/Documentation/i2c/busses/i2c-viapro +++ b/Documentation/i2c/busses/i2c-viapro @@ -19,6 +19,9 @@ Supported adapters: * VIA Technologies, Inc. VX800/VX820 Datasheet: available on http://linux.via.com.tw + * VIA Technologies, Inc. VX855/VX875 + Datasheet: Availability unknown + Authors: Kyösti Mälkki <kmalkki@cc.hut.fi>, Mark D. Studebaker <mdsxyz123@yahoo.com>, @@ -53,6 +56,7 @@ Your lspci -n listing must show one of these : device 1106:3287 (VT8251) device 1106:8324 (CX700) device 1106:8353 (VX800/VX820) + device 1106:8409 (VX855/VX875) If none of these show up, you should look in the BIOS for settings like enable ACPI / SMBus or even USB. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index ad380063077..5578248c18a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -546,6 +546,10 @@ and is between 256 and 4096 characters. It is defined in the file console=brl,ttyS0 For now, only VisioBraille is supported. + consoleblank= [KNL] The console blank (screen saver) timeout in + seconds. Defaults to 10*60 = 10mins. A value of 0 + disables the blank timer. + coredump_filter= [KNL] Change the default value for /proc/<pid>/coredump_filter. diff --git a/Documentation/kmemcheck.txt b/Documentation/kmemcheck.txt new file mode 100644 index 00000000000..363044609da --- /dev/null +++ b/Documentation/kmemcheck.txt @@ -0,0 +1,773 @@ +GETTING STARTED WITH KMEMCHECK +============================== + +Vegard Nossum <vegardno@ifi.uio.no> + + +Contents +======== +0. Introduction +1. Downloading +2. Configuring and compiling +3. How to use +3.1. Booting +3.2. Run-time enable/disable +3.3. Debugging +3.4. Annotating false positives +4. Reporting errors +5. Technical description + + +0. Introduction +=============== + +kmemcheck is a debugging feature for the Linux Kernel. More specifically, it +is a dynamic checker that detects and warns about some uses of uninitialized +memory. + +Userspace programmers might be familiar with Valgrind's memcheck. The main +difference between memcheck and kmemcheck is that memcheck works for userspace +programs only, and kmemcheck works for the kernel only. The implementations +are of course vastly different. Because of this, kmemcheck is not as accurate +as memcheck, but it turns out to be good enough in practice to discover real +programmer errors that the compiler is not able to find through static +analysis. + +Enabling kmemcheck on a kernel will probably slow it down to the extent that +the machine will not be usable for normal workloads such as e.g. an +interactive desktop. kmemcheck will also cause the kernel to use about twice +as much memory as normal. For this reason, kmemcheck is strictly a debugging +feature. + + +1. Downloading +============== + +kmemcheck can only be downloaded using git. If you want to write patches +against the current code, you should use the kmemcheck development branch of +the tip tree. It is also possible to use the linux-next tree, which also +includes the latest version of kmemcheck. + +Assuming that you've already cloned the linux-2.6.git repository, all you +have to do is add the -tip tree as a remote, like this: + + $ git remote add tip git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git + +To actually download the tree, fetch the remote: + + $ git fetch tip + +And to check out a new local branch with the kmemcheck code: + + $ git checkout -b kmemcheck tip/kmemcheck + +General instructions for the -tip tree can be found here: +http://people.redhat.com/mingo/tip.git/readme.txt + + |