| /Linux-v5.4/Documentation/scsi/ |
| D | st.txt | 1 This file contains brief information about the SCSI tape driver.
2 The driver is currently maintained by Kai Mäkisara (email
10 The driver is generic, i.e., it does not contain any code tailored
11 to any specific tape drive. The tape parameters can be specified with
12 one of the following three methods:
14 1. Each user can specify the tape parameters he/she wants to use
17 in a multiuser environment the next user finds the tape parameters in
18 state the previous user left them.
20 2. The system manager (root) can define default values for some tape
21 parameters, like block size and density using the MTSETDRVBUFFER ioctl.
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| /Linux-v5.4/Documentation/admin-guide/pm/ |
| D | cpuidle.rst | 19 Modern processors are generally able to enter states in which the execution of
21 memory or executed. Those states are the *idle* states of the processor.
23 Since part of the processor hardware is not used in idle states, entering them
24 generally allows power drawn by the processor to be reduced and, in consequence,
28 the idle states of processors for this purpose.
33 CPU idle time management operates on CPUs as seen by the *CPU scheduler* (that
34 is the part of the kernel responsible for the distribution of computational
35 work in the system). In its view, CPUs are *logical* units. That is, they need
42 First, if the whole processor can only follow one sequence of instructions (one
43 program) at a time, it is a CPU. In that case, if the hardware is asked to
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| D | cpufreq.rst | 16 The Concept of CPU Performance Scaling
19 The majority of modern processors are capable of operating in a number of
22 the higher the clock frequency and the higher the voltage, the more instructions
23 can be retired by the CPU over a unit of time, but also the higher the clock
24 frequency and the higher the voltage, the more energy is consumed over a unit of
25 time (or the more power is drawn) by the CPU in the given P-state. Therefore
26 there is a natural tradeoff between the CPU capacity (the number of instructions
27 that can be executed over a unit of time) and the power drawn by the CPU.
29 In some situations it is desirable or even necessary to run the program as fast
30 as possible and then there is no reason to use any P-states different from the
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| D | intel_pstate.rst | 16 ``intel_pstate`` is a part of the
17 :doc:`CPU performance scaling subsystem <cpufreq>` in the Linux kernel
18 (``CPUFreq``). It is a scaling driver for the Sandy Bridge and later
21 how ``CPUFreq`` works in general, so this is the time to read :doc:`cpufreq` if
24 For the processors supported by ``intel_pstate``, the P-state concept is broader
25 than just an operating frequency or an operating performance point (see the
27 information about that). For this reason, the representation of P-states used
28 by ``intel_pstate`` internally follows the hardware specification (for details
29 refer to Intel Software Developer’s Manual [2]_). However, the ``CPUFreq`` core
31 frequencies are involved in the user space interface exposed by it, so
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| /Linux-v5.4/Documentation/crypto/ |
| D | userspace-if.rst | 7 The concepts of the kernel crypto API visible to kernel space is fully
8 applicable to the user space interface as well. Therefore, the kernel
9 crypto API high level discussion for the in-kernel use cases applies
12 The major difference, however, is that user space can only act as a
16 The following covers the user space interface exported by the kernel
19 applications that require cryptographic services from the kernel.
21 Some details of the in-kernel kernel crypto API aspects do not apply to
22 user space, however. This includes the difference between synchronous
23 and asynchronous invocations. The user space API call is fully
31 The kernel crypto API is accessible from user space. Currently, the
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| /Linux-v5.4/Documentation/input/ |
| D | multi-touch-protocol.rst | 13 In order to utilize the full power of the new multi-touch and multi-user
15 objects in direct contact with the device surface, is needed. This
16 document describes the multi-touch (MT) protocol which allows kernel
19 The protocol is divided into two types, depending on the capabilities of the
20 hardware. For devices handling anonymous contacts (type A), the protocol
21 describes how to send the raw data for all contacts to the receiver. For
22 devices capable of tracking identifiable contacts (type B), the protocol
33 events. Only the ABS_MT events are recognized as part of a contact
35 applications, the MT protocol can be implemented on top of the ST protocol
39 input_mt_sync() at the end of each packet. This generates a SYN_MT_REPORT
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| /Linux-v5.4/Documentation/filesystems/ |
| D | xfs-delayed-logging-design.txt | 8 such as inodes and dquots, are logged in logical format where the details
9 logged are made up of the changes to in-core structures rather than on-disk
11 logged. The reason for these differences is to reduce the amount of log space
14 than any other object (except maybe the superblock buffer) so keeping the
17 The reason that this is such a concern is that XFS allows multiple separate
18 modifications to a single object to be carried in the log at any given time.
19 This allows the log to avoid needing to flush each change to disk before
20 recording a new change to the object. XFS does this via a method called
22 new change to the object is recorded with a *new copy* of all the existing
23 changes in the new transaction that is written to the log.
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| /Linux-v5.4/include/linux/ |
| D | nvme-fc-driver.h | 15 * For FC LLDD's that are the NVME Host role.
27 * Static fields describing the port being registered:
28 * @node_name: FC WWNN for the port
29 * @port_name: FC WWPN for the port
35 * @port_id: FC N_Port_ID currently assigned the port. Upper 8 bits must
52 * Values set by the NVME-FC layer prior to calling the LLDD ls_req
60 * @timeout: Maximum amount of time, in seconds, to wait for the LS response.
63 * @private: pointer to memory allocated alongside the ls request structure
64 * that is specifically for the LLDD to use while processing the
65 * request. The length of the buffer corresponds to the
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| /Linux-v5.4/Documentation/networking/ |
| D | ppp_generic.txt | 8 The generic PPP driver in linux-2.4 provides an implementation of the
11 * the network interface unit (ppp0 etc.)
12 * the interface to the networking code
15 * the interface to pppd, via a /dev/ppp character device
21 For sending and receiving PPP frames, the generic PPP driver calls on
22 the services of PPP `channels'. A PPP channel encapsulates a
25 has a very simple interface with the generic PPP code: it merely has
33 be linked to each ppp network interface unit. The generic layer is
41 See include/linux/ppp_channel.h for the declaration of the types and
42 functions used to communicate between the generic PPP layer and PPP
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| D | z8530book.rst | 10 The Z85x30 family synchronous/asynchronous controller chips are used on
11 a large number of cheap network interface cards. The kernel provides a
15 The current driver only support synchronous operation. Merging the
18 project for Linux post the 2.4 release
23 The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices in
25 on the chip (each chip has two channels).
27 The PIO synchronous mode supports the most common Z8530 wiring. Here the
28 chip is interface to the I/O and interrupt facilities of the host
29 machine but not to the DMA subsystem. When running PIO the Z8530 has
34 The DMA mode supports the chip when it is configured to use dual DMA
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| /Linux-v5.4/Documentation/locking/ |
| D | rt-mutex-design.rst | 7 Licensed under the GNU Free Documentation License, Version 1.2
10 This document tries to describe the design of the rtmutex.c implementation.
11 It doesn't describe the reasons why rtmutex.c exists. For that please see
13 that happen without this code, but that is in the concept to understand
14 what the code actually is doing.
16 The goal of this document is to help others understand the priority
17 inheritance (PI) algorithm that is used, as well as reasons for the
18 decisions that were made to implement PI in the manner that was done.
26 most of the time it can't be helped. Anytime a high priority process wants
28 the high priority process must wait until the lower priority process is done
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| /Linux-v5.4/Documentation/media/uapi/v4l/ |
| D | dev-decoder.rst | 9 A stateful video decoder takes complete chunks of the bytestream (e.g. Annex-B
11 display order. The decoder is expected not to require any additional information
12 from the client to process these buffers.
14 Performing software parsing, processing etc. of the stream in the driver in
16 operations are needed, use of the Stateless Video Decoder Interface (in
22 1. The general V4L2 API rules apply if not specified in this document
25 2. The meaning of words "must", "may", "should", etc. is as per `RFC
36 depending on decoder capabilities and following the general V4L2 guidelines.
41 7. Given an ``OUTPUT`` buffer A, then A’ represents a buffer on the ``CAPTURE``
50 the destination buffer queue; for decoders, the queue of buffers containing
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| /Linux-v5.4/LICENSES/preferred/ |
| D | LGPL-2.1 | 5 To use this license in source code, put one of the following SPDX
6 tag/value pairs into a comment according to the placement
7 guidelines in the licensing rules documentation.
24 [This is the first released version of the Lesser GPL. It also counts as
25 the successor of the GNU Library Public License, version 2, hence the
30 The licenses for most software are designed to take away your freedom to
31 share and change it. By contrast, the GNU General Public Licenses are
33 make sure the software is free for all its users.
35 This license, the Lesser General Public License, applies to some specially
36 designated software packages--typically libraries--of the Free Software
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| D | LGPL-2.0 | 5 To use this license in source code, put one of the following SPDX
6 tag/value pairs into a comment according to the placement
7 guidelines in the licensing rules documentation.
24 [This is the first released version of the library GPL. It is numbered 2
25 because it goes with version 2 of the ordinary GPL.]
29 The licenses for most software are designed to take away your freedom to
30 share and change it. By contrast, the GNU General Public Licenses are
32 make sure the software is free for all its users.
34 This license, the Library General Public License, applies to some specially
39 General Public Licenses are designed to make sure that you have the freedom
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| /Linux-v5.4/Documentation/vm/ |
| D | hugetlbfs_reserv.rst | 12 task's address space at page fault time if the VMA indicates huge pages are
13 to be used. If no huge page exists at page fault time, the task is sent
16 of huge pages at mmap() time. The idea is that if there were not enough
17 huge pages to cover the mapping, the mmap() would fail. This was first
18 done with a simple check in the code at mmap() time to determine if there
19 were enough free huge pages to cover the mapping. Like most things in the
20 kernel, the code has evolved over time. However, the basic idea was to
22 available for page faults in that mapping. The description below attempts to
23 describe how huge page reserve processing is done in the v4.10 kernel.
32 The Data Structures
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| /Linux-v5.4/Documentation/core-api/ |
| D | debug-objects.rst | 2 The object-lifetime debugging infrastructure
10 debugobjects is a generic infrastructure to track the life time of
11 kernel objects and validate the operations on those.
13 debugobjects is useful to check for the following error patterns:
21 debugobjects is not changing the data structure of the real object so it
28 A kernel subsystem needs to provide a data structure which describes the
29 object type and add calls into the debug code at appropriate places. The
30 data structure to describe the object type needs at minimum the name of
31 the object type. Optional functions can and should be provided to fixup
32 detected problems so the kernel can continue to work and the debug
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| /Linux-v5.4/Documentation/ |
| D | IPMI.txt | 2 The Linux IPMI Driver
7 The Intelligent Platform Management Interface, or IPMI, is a
9 It provides for dynamic discovery of sensors in the system and the
10 ability to monitor the sensors and be informed when the sensor's
17 management software that can use the IPMI system.
19 This document describes how to use the IPMI driver for Linux. If you
20 are not familiar with IPMI itself, see the web site at
27 The Linux IPMI driver is modular, which means you have to pick several
29 these are available in the 'Character Devices' menu then the IPMI
35 The message handler does not provide any user-level interfaces.
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| /Linux-v5.4/tools/perf/pmu-events/arch/x86/silvermont/ |
| D | pipeline.json | 4 …the number of any branch instructions retired. Branch prediction predicts the branch target and e…
10 "BriefDescription": "Counts the number of branch instructions retired..."
14 …the number of conditional branch (JCC) instructions retired. Branch prediction predicts the branch…
20 "BriefDescription": "Counts the number of JCC branch instructions retired"
24 …the number of taken conditional branch (JCC) instructions retired. Branch prediction predicts the …
30 "BriefDescription": "Counts the number of taken JCC branch instructions retired"
34 …the number of near CALL branch instructions retired. Branch prediction predicts the branch target…
40 "BriefDescription": "Counts the number of near CALL branch instructions retired"
44 …the number of near relative CALL branch instructions retired. Branch prediction predicts the bran…
50 "BriefDescription": "Counts the number of near relative CALL branch instructions retired"
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| /Linux-v5.4/Documentation/power/ |
| D | pci.rst | 7 An overview of concepts and the Linux kernel's interfaces related to PCI power
11 This document only covers the aspects of power management specific to PCI
12 devices. For general description of the kernel's interfaces related to device
31 devices into states in which they draw less power (low-power states) at the
35 completely inactive. However, when it is necessary to use the device once
36 again, it has to be put back into the "fully functional" state (full-power
37 state). This may happen when there are some data for the device to handle or
38 as a result of an external event requiring the device to be active, which may
39 be signaled by the device itself.
41 PCI devices may be put into low-power states in two ways, by using the device
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| D | runtime_pm.rst | 15 at the power management core (PM core) level by means of:
17 * The power management workqueue pm_wq in which bus types and device drivers can
24 * A number of runtime PM fields in the 'power' member of 'struct device' (which
25 is of the type 'struct dev_pm_info', defined in include/linux/pm.h) that can
32 used for carrying out runtime PM operations in such a way that the
33 synchronization between them is taken care of by the PM core. Bus types and
36 The runtime PM callbacks present in 'struct dev_pm_ops', the device runtime PM
37 fields of 'struct dev_pm_info' and the core helper functions provided for
53 The ->runtime_suspend(), ->runtime_resume() and ->runtime_idle() callbacks
54 are executed by the PM core for the device's subsystem that may be either of
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| D | userland-swsusp.rst | 7 First, the warnings at the beginning of swsusp.txt still apply.
9 Second, you should read the FAQ in swsusp.txt _now_ if you have not
12 Now, to use the userland interface for software suspend you need special
13 utilities that will read/write the system memory snapshot from/to the
18 The interface consists of a character device providing the open(),
20 commands defined in include/linux/suspend_ioctls.h . The major and minor
21 numbers of the device are, respectively, 10 and 231, and they can
24 The device can be open either for reading or for writing. If open for
25 reading, it is considered to be in the suspend mode. Otherwise it is
26 assumed to be in the resume mode. The device cannot be open for simultaneous
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| /Linux-v5.4/drivers/staging/speakup/ |
| D | spkguide.txt | 2 The Speakup User's Guide
11 Copyright (c) 2009, 2010 the Speakup Team
14 under the terms of the GNU Free Documentation License, Version 1.2 or
15 any later version published by the Free Software Foundation; with no
17 copy of the license is included in the section entitled "GNU Free
22 The purpose of this document is to familiarize users with the user
24 for installing or obtaining Speakup, visit the web site at
25 http://linux-speakup.org/. Speakup is a set of patches to the standard
27 a part of a monolithic kernel. These details are beyond the scope of
28 this manual, but the user may need to be aware of the module
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| /Linux-v5.4/Documentation/admin-guide/mm/ |
| D | userfaultfd.rst | 10 Userfaults allow the implementation of on-demand paging from userland
12 memory page faults, something otherwise only the kernel code could do.
15 of the PROT_NONE+SIGSEGV trick.
20 Userfaults are delivered and resolved through the userfaultfd syscall.
22 The userfaultfd (aside from registering and unregistering virtual
25 1) read/POLLIN protocol to notify a userland thread of the faults
28 2) various UFFDIO_* ioctls that can manage the virtual memory regions
29 registered in the userfaultfd that allows userland to efficiently
30 resolve the userfaults it receives via 1) or to manage the virtual
31 memory in the background
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| /Linux-v5.4/Documentation/admin-guide/device-mapper/ |
| D | dm-integrity.rst | 5 The dm-integrity target emulates a block device that has additional
9 writing the sector and the integrity tag must be atomic - i.e. in case of
12 To guarantee write atomicity, the dm-integrity target uses journal, it
13 writes sector data and integrity tags into a journal, commits the journal
14 and then copies the data and integrity tags to their respective location.
16 The dm-integrity target can be used with the dm-crypt target - in this
17 situation the dm-crypt target creates the integrity data and passes them
18 to the dm-integrity target via bio_integrity_payload attached to the bio.
19 In this mode, the dm-crypt and dm-integrity targets provide authenticated
20 disk encryption - if the attacker modifies the encrypted device, an I/O
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| /Linux-v5.4/Documentation/timers/ |
| D | highres.rst | 5 Further information can be found in the paper of the OLS 2006 talk "hrtimers
6 and beyond". The paper is part of the OLS 2006 Proceedings Volume 1, which can
7 be found on the OLS website:
10 The slides to this talk are available from:
13 The slides contain five figures (pages 2, 15, 18, 20, 22), which illustrate the
14 changes in the time(r) related Linux subsystems. Figure #1 (p. 2) shows the
15 design of the Linux time(r) system before hrtimers and other building blocks
18 Note: the paper and the slides are talking about "clock event source", while we
19 switched to the name "clock event devices" in meantime.
21 The design contains the following basic building blocks:
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