| /Linux-v4.19/Documentation/sysctl/ |
| D | user.txt | 10 limits on the number of namespaces and other objects that have
13 The primary purpose of these limits is to stop programs that
16 intention that the defaults of these limits are set high enough that
21 verified to be below the per user limit in that user namespace.
28 This recursive counting of created objects ensures that creating a
35 The maximum number of cgroup namespaces that any user in the current
40 The maximum number of ipc namespaces that any user in the current
45 The maximum number of mount namespaces that any user in the current
50 The maximum number of network namespaces that any user in the
55 The maximum number of pid namespaces that any user in the current
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| /Linux-v4.19/Documentation/process/ |
| D | management-style.rst | 13 to do with reality. It started as a lark, but that doesn't mean that it
26 making it painfully obvious to the questioner that we don't have a clue
36 Everybody thinks managers make decisions, and that decision-making is
46 competent to make that decision for them.
50 Namely that you are in the wrong job, and that **they** should be managing
59 It helps to realize that the key difference between a big decision and a
61 can be made small by just always making sure that if you were wrong (and
66 And people will even see that as true leadership (*cough* bullshit
70 things that can't be undone. Don't get ushered into a corner from which
74 It turns out that since nobody would be stupid enough to ever really let
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| D | 6.Followthrough.rst | 8 patches. One of the biggest mistakes that even experienced kernel
9 developers can make is to conclude that their work is now done. In truth,
13 It is a rare patch which is so good at its first posting that there is no
16 code. You, as the author of that code, will be expected to work with the
17 kernel community to ensure that your code is up to the kernel's quality
32 value and why you went to the trouble of writing it. But that value
36 to substantial rewrites - come from the understanding that Linux will
49 be working on the kernel years from now, but they understand that their
54 What all of this comes down to is that, when reviewers send you comments,
55 you need to pay attention to the technical observations that they are
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| /Linux-v4.19/Documentation/ |
| D | DMA-attributes.txt | 5 This document describes the semantics of the DMA attributes that are
21 useful, suppose that a device does a DMA write to indicate that data is
29 DMA_ATTR_WEAK_ORDERING specifies that reads and writes to the mapping
30 may be weakly ordered, that is that reads and writes may pass each other.
33 those that do not will simply ignore the attribute and exhibit default
39 DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be
43 those that do not will simply ignore the attribute and exhibit default
51 you are guaranteeing to the platform that you have all the correct and
63 that you won't dereference the pointer returned by dma_alloc_attr(). You
64 can treat it as a cookie that must be passed to dma_mmap_attrs() and
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| /Linux-v4.19/Documentation/vm/ |
| D | active_mm.rst | 14 Cc'd to linux-kernel, because I don't write explanations all that often,
27 difference is that an anonymous address space doesn't care about the
32 The obvious use for a "anonymous address space" is any thread that
34 this category, but even "real" threads can temporarily say that for
36 and that the scheduler might as well try to avoid wasting time on
38 sync does that.
41 tsk->mm will be NULL, for the logical reason that an anonymous process
45 "stole" for such an anonymous user. For that, we have "tsk->active_mm",
48 The rule is that for a process with a real address space (ie tsk->mm is
57 To support all that, the "struct mm_struct" now has two counters: a
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| D | highmem.rst | 15 exceeds the maximum size of virtual memory. At that point it becomes
18 the pieces of physical memory that it wants to access.
22 where exactly that border lies.
25 VM space so that we don't have to pay the full TLB invalidation costs for
40 This means that the kernel can at most map 1GiB of physical memory at any one
45 Other architectures that have mm context tagged TLBs can have separate kernel
65 page. Since the mapping is restricted to the CPU that issued it, it
66 performs well, but the issuing task is therefore required to stay on that
72 It may be assumed that k[un]map_atomic() won't fail.
79 wants to access the contents of a page that might be allocated from high memory
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| /Linux-v4.19/Documentation/driver-model/ |
| D | binding.txt | 5 driver that can control it. Bus drivers have typically handled this
14 The bus type structure contains a list of all devices that are on that bus
17 list of all drivers of that bus type. When driver_register is called
26 to find one that supports it. In order to determine that, the device
27 ID of the device must match one of the device IDs that the driver
38 chance to verify that it really does support the hardware, and that
46 class, and that is set in the driver's devclass field.
62 A symlink is created in the bus's 'devices' directory that points to
65 A symlink is created in the driver's 'devices' directory that points
69 symlink is created in that directory that points to the device's
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| /Linux-v4.19/Documentation/power/ |
| D | freezing-of-tasks.txt | 12 There are three per-task flags used for that, PF_NOFREEZE, PF_FROZEN
13 and PF_FREEZER_SKIP (the last one is auxiliary). The tasks that have
23 sets this variable. After this, it executes try_to_freeze_tasks() that sends a
25 All freezable tasks must react to that by calling try_to_freeze(), which
28 it loop until PF_FROZEN is cleared for it. Then, we say that the task is
35 try_to_freeze() function (defined in include/linux/freezer.h), that checks
42 that combine interruptible sleep with checking if the task is to be frozen and
64 order to clear the PF_FROZEN flag for each frozen task. Then, the tasks that
95 IV. Why do we do that?
104 filesystem-related information that must be consistent with the state of the
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| D | s2ram.txt | 9 2) If that does not help, try reading tricks.txt and
19 always it's a driver that is buggy. Thank God for the suspend/resume
20 debugging - the thing that Chuck tried to disable. That's often the _only_
23 driver that doesn't resume and recompile and reboot).
26 machine that doesn't boot) is:
47 which means that the last trace event was just before trying to resume
48 device 0000:01:00.0. Then figure out what driver is controlling that
53 the culprit may be a device from a loadable kernel module that is not loaded
61 that "radeonfb" simply cannot resume that device - it tries to set the
68 Reason for this is that the RTC is the only reliably available piece of
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| D | suspend-and-interrupts.txt | 11 suspend after the "late" phase of suspending devices (that is, after all of the
15 The rationale for doing so is that after the "late" phase of device suspend
19 interrupt handlers for shared IRQs that device drivers implementing them were
28 of resuming devices (that is, before starting to execute ->resume_early
29 callbacks for devices). The function doing that is resume_device_irqs().
35 There are interrupts that can legitimately trigger during the entire system
41 The IRQF_NO_SUSPEND flag is used to indicate that to the IRQ subsystem when
44 expected during the suspend-resume cycle, but does not guarantee that the
48 Note that the IRQF_NO_SUSPEND flag affects the entire IRQ and not just one
64 (such as an SoC) so that signals from a given line are routed in a different way
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| /Linux-v4.19/Documentation/filesystems/ |
| D | directory-locking | 7 that "inode pointer" order in the following.
20 4) rename() that is _not_ cross-directory. Locking rules: caller locks
31 * check that source is not a directory
52 The rules above obviously guarantee that all directories that are going to be
92 blocked on source and it means that it doesn't hold any locks.
95 has a child that is also contended. Indeed, suppose that it is held by
97 is blocked on belongs to child of that object due to (1).
99 It means that one of the operations is cross-directory rename.
101 would have a contended child and we had assumed that no object is its
107 would again have an infinite set of contended objects). But that
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| /Linux-v4.19/Documentation/powerpc/ |
| D | qe_firmware.txt | 31 the particular license, please see the license text that is distributed with
45 integers that compose the actual QE microcode.
47 The term 'firmware' refers to a binary blob that contains the microcode as
48 well as other data that
55 Firmware files are binary files that contain only a firmware.
70 needs split I-RAM. Split I-RAM is only meaningful for SOCs that have
80 5) If necessary, device drivers that need the virtual traps and extended mode
91 This structure contains 6 words that the application should copy to some
119 This is a double word bit array (64 bits) that defines special functionality
127 | 0 | General | Indicates that prior to each host command |
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| /Linux-v4.19/Documentation/i2c/ |
| D | fault-codes | 9 faults. There may be fancier recovery schemes that are appropriate in
14 result for an operation ... it doesn't indicate that anything is wrong
15 at all, just that the outcome wasn't on the "golden path".
19 the right fault code, so that it can (in turn) behave correctly.
29 Note that the descriptions here are not exhaustive. There are other
30 codes that may be returned, and other cases where these codes should
44 atomic context, when some task is already using that I2C bus
53 host. Note that even if PECs are in use, you should not rely
60 or that the reset was attempted but failed.
81 Returned by any component that can't allocate memory when
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| /Linux-v4.19/Documentation/acpi/ |
| D | osi.txt | 7 can evaluate that method, look to see if it supports 'XYZ'
11 that OSPM supports"
19 Linux runs on two groups of machines -- those that are tested by the OEM
20 to be compatible with Linux, and those that were never tested with Linux,
23 The larger group is the systems tested to run only Windows. Not only that,
27 Experience shows that taking untested paths through the BIOS
34 Windows to its list of _OSI strings. So it is possible that additional strings
36 But it is likely that they will all eventually be added.
49 via the linux-acpi@vger.kernel.org mailing list. When that patch
52 by the OS. Linux distributors can back-port that patch for Linux
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| /Linux-v4.19/Documentation/RCU/ |
| D | stallwarn.txt | 5 options that can be used to fine-tune the detector's operation. Finally,
31 o Booting Linux using a console connection that is too slow to
38 o Anything that prevents RCU's grace-period kthreads from running.
48 that low-priority task is not permitted to run on any other CPU,
54 o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that
66 Note that certain high-overhead debugging options, for example
74 slow system. Note that thermal throttling and on-demand governors
78 interrupt on a CPU that is not in dyntick-idle mode. This
88 leading the realization that the CPU had failed.
91 warning. Note that SRCU does -not- have CPU stall warnings. Please note
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| D | rcu_dereference.txt | 14 bugs due to games that compilers and DEC Alpha can play.
18 DEC Alpha can load a pointer, dereference that pointer, and
19 return data preceding initialization that preceded the store of
31 There are a very few exceptions, namely that you can temporarily
35 bits of that pointer. This clearly means that the pointer
48 rights to substitute zero for this sort of expression, so that
53 and "b" are integers that happen to be equal, the expression
57 o If you are using RCU to protect JITed functions, so that the
62 using the same memory that was used by an earlier JITed function.
78 As before, the reason this is buggy is that relational operators
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| D | rcu.txt | 5 operations into two parts, one that prevents anyone from seeing the data
6 item being destroyed, and one that actually carries out the destruction.
8 must be long enough that any readers accessing the item being deleted have
19 The advantage of RCU's two-part approach is that RCU readers need
22 barriers. The fact that these operations are quite expensive
24 in read-mostly situations. The fact that RCU readers need not
33 three states, we know that that CPU has exited any previous RCU
37 safely free up that item.
40 same effect, but require that the readers manipulate CPU-local
62 o What guidelines should I follow when writing code that uses RCU?
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| /Linux-v4.19/Documentation/media/uapi/v4l/ |
| D | colorspaces.rst | 10 biology. Just because you have three numbers that describe the 'red',
11 'green' and 'blue' components of the color of a pixel does not mean that
12 you can accurately display that color. A colorspace defines what it
17 In order to do that we first need to have a good definition of color,
18 i.e. some way to uniquely and unambiguously define a color so that
20 the human eye has color receptors that are sensitive to three different
34 possible that different SPDs will result in the same stimulation of
39 between SPDs and the perceived color and that resulted in the CIE 1931
40 standard that defines spectral weighting functions that model the
41 perception of color. Specifically that standard defines functions that
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| /Linux-v4.19/Documentation/filesystems/ext4/ondisk/ |
| D | allocators.rst | 6 ext4 recognizes (better than ext3, anyway) that data locality is
9 that the head actuator and disk must perform to access a data block,
17 The first tool that ext4 uses to combat fragmentation is the multi-block
20 that the space will get written soon. When the file is closed, the
24 extent. A second related trick that ext4 uses is delayed allocation.
30 is that the filesystem can make better location decisions.
32 The third trick that ext4 (and ext3) uses is that it tries to keep a
38 The fourth trick is that all the inodes in a directory are placed in the
40 here is that all the files in a directory might be related, therefore it
43 The fifth trick is that the disk volume is cut up into 128MB block
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| /Linux-v4.19/Documentation/media/uapi/cec/ |
| D | cec-ioc-dqevent.rst | 40 the new one. This means that intermediate results can be thrown away but
41 that the latest event is always available. This also means that is it
42 possible to read two successive events that have the same value (e.g.
44 the same state). In that case the intermediate state changes were lost but
45 it is guaranteed that the state did change in between the two events.
65 has the unregistered logical address. In that case all other bits are 0.
84 size of the message queue guarantees that all messages received in
142 called an initial event will be generated for that filehandle with
143 the CEC Adapter's state at that time.
155 Only applies to adapters that have the ``CEC_CAP_MONITOR_PIN``
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| /Linux-v4.19/LICENSES/preferred/ |
| D | LGPL-2.1 | 43 price. Our General Public Licenses are designed to make sure that you have
45 service if you wish); that you receive source code or can get it if you
46 want it; that you can change the software and use pieces of it in new free
47 programs; and that you are informed that you can do these things.
49 To protect your rights, we need to make restrictions that forbid
55 a fee, you must give the recipients all the rights that we gave you. You
56 must make sure that they, too, receive or can get the source code. If you
58 the recipients, so that they can relink them with the library after making
66 To protect each distributor, we want to make it very clear that there is no
68 else and passed on, the recipients should know that what they have is not
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| D | LGPL-2.0 | 39 General Public Licenses are designed to make sure that you have the freedom
41 wish), that you receive source code or can get it if you want it, that you
42 can change the software or use pieces of it in new free programs; and that
45 To protect your rights, we need to make restrictions that forbid anyone to
51 a fee, you must give the recipients all the rights that we gave you. You
52 must make sure that they, too, receive or can get the source code. If you
54 the recipients so that they can relink them with the library, after making
62 Also, for each distributor's protection, we want to make certain that
63 everyone understands that there is no warranty for this free library. If
65 recipients to know that what they have is not the original version, so that
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| /Linux-v4.19/Documentation/namespaces/ |
| D | resource-control.txt | 1 There are a lot of kinds of objects in the kernel that don't have
2 individual limits or that have limits that are ineffective when a set
7 Therefore it is recommended that memory control groups be enabled in
8 kernels that enable user namespaces, and it is further recommended
9 that userspace configure memory control groups to limit how much
|
| /Linux-v4.19/Documentation/locking/ |
| D | rt-mutex-design.txt | 10 It doesn't describe the reasons why rtmutex.c exists. For that please see
12 that happen without this code, but that is in the concept to understand
16 inheritance (PI) algorithm that is used, as well as reasons for the
17 decisions that were made to implement PI in the manner that was done.
26 to use a resource that a lower priority process has (a mutex for example),
36 that C owns and must wait and lets C run to release the lock. But in the
70 inherited priority, and A then can continue with the resource that C had.
75 Here I explain some terminology that is used in this document to help describe
76 the design that is used to implement PI.
78 PI chain - The PI chain is an ordered series of locks and processes that cause
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| /Linux-v4.19/Documentation/driver-api/fpga/ |
| D | intro.rst | 10 enumeration) from lower layers that know how to program a specific
14 should go without saying. If that seems necessary, there's probably
15 framework functionality that can be added that will benefit
17 seek out a solution that expands the framework for broad reuse.
29 includes the framework in fpga-mgr.c and the low level drivers that
38 actual hard hardware that gates a bus to a CPU or a soft ("freeze")
39 bridge in FPGA fabric that surrounds a partial reconfiguration region
41 drivers that are registered with it.
|
