Merge branch 'docs-next' of git://git.lwn.net/linux-2.6
* 'docs-next' of git://git.lwn.net/linux-2.6: docs: update the development process document docs: fix dev_debug() braino in dynamic-debug-howto.txt
This commit is contained in:
Linus Torvalds
commit
93567c43eb
8 changed files with 165 additions and 126 deletions
|
|
@ -56,13 +56,13 @@ information on kernel development.
|
|||
|
||||
1.2: WHAT THIS DOCUMENT IS ABOUT
|
||||
|
||||
The Linux kernel, at over 6 million lines of code and well over 1000 active
|
||||
contributors, is one of the largest and most active free software projects
|
||||
in existence. Since its humble beginning in 1991, this kernel has evolved
|
||||
into a best-of-breed operating system component which runs on pocket-sized
|
||||
digital music players, desktop PCs, the largest supercomputers in
|
||||
existence, and all types of systems in between. It is a robust, efficient,
|
||||
and scalable solution for almost any situation.
|
||||
The Linux kernel, at over 8 million lines of code and well over 1000
|
||||
contributors to each release, is one of the largest and most active free
|
||||
software projects in existence. Since its humble beginning in 1991, this
|
||||
kernel has evolved into a best-of-breed operating system component which
|
||||
runs on pocket-sized digital music players, desktop PCs, the largest
|
||||
supercomputers in existence, and all types of systems in between. It is a
|
||||
robust, efficient, and scalable solution for almost any situation.
|
||||
|
||||
With the growth of Linux has come an increase in the number of developers
|
||||
(and companies) wishing to participate in its development. Hardware
|
||||
|
|
|
|||
|
|
@ -14,16 +14,15 @@ The kernel developers use a loosely time-based release process, with a new
|
|||
major kernel release happening every two or three months. The recent
|
||||
release history looks like this:
|
||||
|
||||
2.6.26 July 13, 2008
|
||||
2.6.25 April 16, 2008
|
||||
2.6.24 January 24, 2008
|
||||
2.6.23 October 9, 2007
|
||||
2.6.22 July 8, 2007
|
||||
2.6.21 April 25, 2007
|
||||
2.6.20 February 4, 2007
|
||||
2.6.38 March 14, 2011
|
||||
2.6.37 January 4, 2011
|
||||
2.6.36 October 20, 2010
|
||||
2.6.35 August 1, 2010
|
||||
2.6.34 May 15, 2010
|
||||
2.6.33 February 24, 2010
|
||||
|
||||
Every 2.6.x release is a major kernel release with new features, internal
|
||||
API changes, and more. A typical 2.6 release can contain over 10,000
|
||||
API changes, and more. A typical 2.6 release can contain nearly 10,000
|
||||
changesets with changes to several hundred thousand lines of code. 2.6 is
|
||||
thus the leading edge of Linux kernel development; the kernel uses a
|
||||
rolling development model which is continually integrating major changes.
|
||||
|
|
@ -42,13 +41,13 @@ merge window do not come out of thin air; they have been collected, tested,
|
|||
and staged ahead of time. How that process works will be described in
|
||||
detail later on).
|
||||
|
||||
The merge window lasts for two weeks. At the end of this time, Linus
|
||||
Torvalds will declare that the window is closed and release the first of
|
||||
the "rc" kernels. For the kernel which is destined to be 2.6.26, for
|
||||
example, the release which happens at the end of the merge window will be
|
||||
called 2.6.26-rc1. The -rc1 release is the signal that the time to merge
|
||||
new features has passed, and that the time to stabilize the next kernel has
|
||||
begun.
|
||||
The merge window lasts for approximately two weeks. At the end of this
|
||||
time, Linus Torvalds will declare that the window is closed and release the
|
||||
first of the "rc" kernels. For the kernel which is destined to be 2.6.40,
|
||||
for example, the release which happens at the end of the merge window will
|
||||
be called 2.6.40-rc1. The -rc1 release is the signal that the time to
|
||||
merge new features has passed, and that the time to stabilize the next
|
||||
kernel has begun.
|
||||
|
||||
Over the next six to ten weeks, only patches which fix problems should be
|
||||
submitted to the mainline. On occasion a more significant change will be
|
||||
|
|
@ -66,20 +65,19 @@ will get up to somewhere between -rc6 and -rc9 before the kernel is
|
|||
considered to be sufficiently stable and the final 2.6.x release is made.
|
||||
At that point the whole process starts over again.
|
||||
|
||||
As an example, here is how the 2.6.25 development cycle went (all dates in
|
||||
2008):
|
||||
As an example, here is how the 2.6.38 development cycle went (all dates in
|
||||
2011):
|
||||
|
||||
January 24 2.6.24 stable release
|
||||
February 10 2.6.25-rc1, merge window closes
|
||||
February 15 2.6.25-rc2
|
||||
February 24 2.6.25-rc3
|
||||
March 4 2.6.25-rc4
|
||||
March 9 2.6.25-rc5
|
||||
March 16 2.6.25-rc6
|
||||
March 25 2.6.25-rc7
|
||||
April 1 2.6.25-rc8
|
||||
April 11 2.6.25-rc9
|
||||
April 16 2.6.25 stable release
|
||||
January 4 2.6.37 stable release
|
||||
January 18 2.6.38-rc1, merge window closes
|
||||
January 21 2.6.38-rc2
|
||||
February 1 2.6.38-rc3
|
||||
February 7 2.6.38-rc4
|
||||
February 15 2.6.38-rc5
|
||||
February 21 2.6.38-rc6
|
||||
March 1 2.6.38-rc7
|
||||
March 7 2.6.38-rc8
|
||||
March 14 2.6.38 stable release
|
||||
|
||||
How do the developers decide when to close the development cycle and create
|
||||
the stable release? The most significant metric used is the list of
|
||||
|
|
@ -99,26 +97,34 @@ kernels go out with a handful of known regressions though, hopefully, none
|
|||
of them are serious.
|
||||
|
||||
Once a stable release is made, its ongoing maintenance is passed off to the
|
||||
"stable team," currently comprised of Greg Kroah-Hartman and Chris Wright.
|
||||
The stable team will release occasional updates to the stable release using
|
||||
the 2.6.x.y numbering scheme. To be considered for an update release, a
|
||||
patch must (1) fix a significant bug, and (2) already be merged into the
|
||||
mainline for the next development kernel. Continuing our 2.6.25 example,
|
||||
the history (as of this writing) is:
|
||||
"stable team," currently consisting of Greg Kroah-Hartman. The stable team
|
||||
will release occasional updates to the stable release using the 2.6.x.y
|
||||
numbering scheme. To be considered for an update release, a patch must (1)
|
||||
fix a significant bug, and (2) already be merged into the mainline for the
|
||||
next development kernel. Kernels will typically receive stable updates for
|
||||
a little more than one development cycle past their initial release. So,
|
||||
for example, the 2.6.36 kernel's history looked like:
|
||||
|
||||
May 1 2.6.25.1
|
||||
May 6 2.6.25.2
|
||||
May 9 2.6.25.3
|
||||
May 15 2.6.25.4
|
||||
June 7 2.6.25.5
|
||||
June 9 2.6.25.6
|
||||
June 16 2.6.25.7
|
||||
June 21 2.6.25.8
|
||||
June 24 2.6.25.9
|
||||
October 10 2.6.36 stable release
|
||||
November 22 2.6.36.1
|
||||
December 9 2.6.36.2
|
||||
January 7 2.6.36.3
|
||||
February 17 2.6.36.4
|
||||
|
||||
Stable updates for a given kernel are made for approximately six months;
|
||||
after that, the maintenance of stable releases is solely the responsibility
|
||||
of the distributors which have shipped that particular kernel.
|
||||
2.6.36.4 was the final stable update for the 2.6.36 release.
|
||||
|
||||
Some kernels are designated "long term" kernels; they will receive support
|
||||
for a longer period. As of this writing, the current long term kernels
|
||||
and their maintainers are:
|
||||
|
||||
2.6.27 Willy Tarreau (Deep-frozen stable kernel)
|
||||
2.6.32 Greg Kroah-Hartman
|
||||
2.6.35 Andi Kleen (Embedded flag kernel)
|
||||
|
||||
The selection of a kernel for long-term support is purely a matter of a
|
||||
maintainer having the need and the time to maintain that release. There
|
||||
are no known plans for long-term support for any specific upcoming
|
||||
release.
|
||||
|
||||
|
||||
2.2: THE LIFECYCLE OF A PATCH
|
||||
|
|
@ -193,8 +199,8 @@ involved.
|
|||
2.3: HOW PATCHES GET INTO THE KERNEL
|
||||
|
||||
There is exactly one person who can merge patches into the mainline kernel
|
||||
repository: Linus Torvalds. But, of the over 12,000 patches which went
|
||||
into the 2.6.25 kernel, only 250 (around 2%) were directly chosen by Linus
|
||||
repository: Linus Torvalds. But, of the over 9,500 patches which went
|
||||
into the 2.6.38 kernel, only 112 (around 1.3%) were directly chosen by Linus
|
||||
himself. The kernel project has long since grown to a size where no single
|
||||
developer could possibly inspect and select every patch unassisted. The
|
||||
way the kernel developers have addressed this growth is through the use of
|
||||
|
|
@ -264,8 +270,8 @@ subsystem tree of last resort; if there is no other obvious path for a
|
|||
patch into the mainline, it is likely to end up in -mm. Miscellaneous
|
||||
patches which accumulate in -mm will eventually either be forwarded on to
|
||||
an appropriate subsystem tree or be sent directly to Linus. In a typical
|
||||
development cycle, approximately 10% of the patches going into the mainline
|
||||
get there via -mm.
|
||||
development cycle, approximately 5-10% of the patches going into the
|
||||
mainline get there via -mm.
|
||||
|
||||
The current -mm patch is available in the "mmotm" (-mm of the moment)
|
||||
directory at:
|
||||
|
|
@ -275,7 +281,7 @@ directory at:
|
|||
Use of the MMOTM tree is likely to be a frustrating experience, though;
|
||||
there is a definite chance that it will not even compile.
|
||||
|
||||
The other -next tree, started more recently, is linux-next, maintained by
|
||||
The primary tree for next-cycle patch merging is linux-next, maintained by
|
||||
Stephen Rothwell. The linux-next tree is, by design, a snapshot of what
|
||||
the mainline is expected to look like after the next merge window closes.
|
||||
Linux-next trees are announced on the linux-kernel and linux-next mailing
|
||||
|
|
@ -287,25 +293,14 @@ Some information about linux-next has been gathered at:
|
|||
|
||||
http://linux.f-seidel.de/linux-next/pmwiki/
|
||||
|
||||
How the linux-next tree will fit into the development process is still
|
||||
changing. As of this writing, the first full development cycle involving
|
||||
linux-next (2.6.26) is coming to an end; thus far, it has proved to be a
|
||||
valuable resource for finding and fixing integration problems before the
|
||||
beginning of the merge window. See http://lwn.net/Articles/287155/ for
|
||||
more information on how linux-next has worked to set up the 2.6.27 merge
|
||||
window.
|
||||
Linux-next has become an integral part of the kernel development process;
|
||||
all patches merged during a given merge window should really have found
|
||||
their way into linux-next some time before the merge window opens.
|
||||
|
||||
Some developers have begun to suggest that linux-next should be used as the
|
||||
target for future development as well. The linux-next tree does tend to be
|
||||
far ahead of the mainline and is more representative of the tree into which
|
||||
any new work will be merged. The downside to this idea is that the
|
||||
volatility of linux-next tends to make it a difficult development target.
|
||||
See http://lwn.net/Articles/289013/ for more information on this topic, and
|
||||
stay tuned; much is still in flux where linux-next is involved.
|
||||
|
||||
2.4.1: STAGING TREES
|
||||
|
||||
The kernel source tree now contains the drivers/staging/ directory, where
|
||||
The kernel source tree contains the drivers/staging/ directory, where
|
||||
many sub-directories for drivers or filesystems that are on their way to
|
||||
being added to the kernel tree live. They remain in drivers/staging while
|
||||
they still need more work; once complete, they can be moved into the
|
||||
|
|
@ -313,15 +308,23 @@ kernel proper. This is a way to keep track of drivers that aren't
|
|||
up to Linux kernel coding or quality standards, but people may want to use
|
||||
them and track development.
|
||||
|
||||
Greg Kroah-Hartman currently (as of 2.6.36) maintains the staging tree.
|
||||
Drivers that still need work are sent to him, with each driver having
|
||||
its own subdirectory in drivers/staging/. Along with the driver source
|
||||
files, a TODO file should be present in the directory as well. The TODO
|
||||
file lists the pending work that the driver needs for acceptance into
|
||||
the kernel proper, as well as a list of people that should be Cc'd for any
|
||||
patches to the driver. Staging drivers that don't currently build should
|
||||
have their config entries depend upon CONFIG_BROKEN. Once they can
|
||||
be successfully built without outside patches, CONFIG_BROKEN can be removed.
|
||||
Greg Kroah-Hartman currently maintains the staging tree. Drivers that
|
||||
still need work are sent to him, with each driver having its own
|
||||
subdirectory in drivers/staging/. Along with the driver source files, a
|
||||
TODO file should be present in the directory as well. The TODO file lists
|
||||
the pending work that the driver needs for acceptance into the kernel
|
||||
proper, as well as a list of people that should be Cc'd for any patches to
|
||||
the driver. Current rules require that drivers contributed to staging
|
||||
must, at a minimum, compile properly.
|
||||
|
||||
Staging can be a relatively easy way to get new drivers into the mainline
|
||||
where, with luck, they will come to the attention of other developers and
|
||||
improve quickly. Entry into staging is not the end of the story, though;
|
||||
code in staging which is not seeing regular progress will eventually be
|
||||
removed. Distributors also tend to be relatively reluctant to enable
|
||||
staging drivers. So staging is, at best, a stop on the way toward becoming
|
||||
a proper mainline driver.
|
||||
|
||||
|
||||
2.5: TOOLS
|
||||
|
||||
|
|
@ -347,11 +350,7 @@ page at:
|
|||
|
||||
http://git-scm.com/
|
||||
|
||||
That page has pointers to documentation and tutorials. One should be
|
||||
aware, in particular, of the Kernel Hacker's Guide to git, which has
|
||||
information specific to kernel development:
|
||||
|
||||
http://linux.yyz.us/git-howto.html
|
||||
That page has pointers to documentation and tutorials.
|
||||
|
||||
Among the kernel developers who do not use git, the most popular choice is
|
||||
almost certainly Mercurial:
|
||||
|
|
|
|||
|
|
@ -110,8 +110,8 @@ the kernel community's standards. Some examples include:
|
|||
|
||||
- The AppArmor security module made use of internal virtual filesystem
|
||||
data structures in ways which were considered to be unsafe and
|
||||
unreliable. This code has since been significantly reworked, but
|
||||
remains outside of the mainline.
|
||||
unreliable. This concern (among others) kept AppArmor out of the
|
||||
mainline for years.
|
||||
|
||||
In each of these cases, a great deal of pain and extra work could have been
|
||||
avoided with some early discussion with the kernel developers.
|
||||
|
|
@ -138,6 +138,19 @@ patches, and who, if anybody, is attaching Signed-off-by lines to those
|
|||
patches. Those are the people who will be best placed to help with a new
|
||||
development project.
|
||||
|
||||
The task of finding the right maintainer is sometimes challenging enough
|
||||
that the kernel developers have added a script to ease the process:
|
||||
|
||||
.../scripts/get_maintainer.pl
|
||||
|
||||
This script will return the current maintainer(s) for a given file or
|
||||
directory when given the "-f" option. If passed a patch on the
|
||||
command line, it will list the maintainers who should probably receive
|
||||
copies of the patch. There are a number of options regulating how hard
|
||||
get_maintainer.pl will search for maintainers; please be careful about
|
||||
using the more aggressive options as you may end up including developers
|
||||
who have no real interest in the code you are modifying.
|
||||
|
||||
If all else fails, talking to Andrew Morton can be an effective way to
|
||||
track down a maintainer for a specific piece of code.
|
||||
|
||||
|
|
@ -155,11 +168,15 @@ reaction, but, instead, little or no reaction at all. The sad truth of the
|
|||
matter is (1) kernel developers tend to be busy, (2) there is no shortage
|
||||
of people with grand plans and little code (or even prospect of code) to
|
||||
back them up, and (3) nobody is obligated to review or comment on ideas
|
||||
posted by others. If a request-for-comments posting yields little in the
|
||||
way of comments, do not assume that it means there is no interest in the
|
||||
project. Unfortunately, you also cannot assume that there are no problems
|
||||
with your idea. The best thing to do in this situation is to proceed,
|
||||
keeping the community informed as you go.
|
||||
posted by others. Beyond that, high-level designs often hide problems
|
||||
which are only reviewed when somebody actually tries to implement those
|
||||
designs; for that reason, kernel developers would rather see the code.
|
||||
|
||||
If a request-for-comments posting yields little in the way of comments, do
|
||||
not assume that it means there is no interest in the project.
|
||||
Unfortunately, you also cannot assume that there are no problems with your
|
||||
idea. The best thing to do in this situation is to proceed, keeping the
|
||||
community informed as you go.
|
||||
|
||||
|
||||
3.5: GETTING OFFICIAL BUY-IN
|
||||
|
|
|
|||
|
|
@ -131,6 +131,11 @@ classic time/space tradeoff taught in beginning data structures classes
|
|||
often does not apply to contemporary hardware. Space *is* time, in that a
|
||||
larger program will run slower than one which is more compact.
|
||||
|
||||
More recent compilers take an increasingly active role in deciding whether
|
||||
a given function should actually be inlined or not. So the liberal
|
||||
placement of "inline" keywords may not just be excessive; it could also be
|
||||
irrelevant.
|
||||
|
||||
|
||||
* Locking
|
||||
|
||||
|
|
@ -285,6 +290,13 @@ be found at https://sparse.wiki.kernel.org/index.php/Main_Page if your
|
|||
distributor does not package it); it can then be run on the code by adding
|
||||
"C=1" to your make command.
|
||||
|
||||
The "Coccinelle" tool (http://coccinelle.lip6.fr/) is able to find a wide
|
||||
variety of potential coding problems; it can also propose fixes for those
|
||||
problems. Quite a few "semantic patches" for the kernel have been packaged
|
||||
under the scripts/coccinelle directory; running "make coccicheck" will run
|
||||
through those semantic patches and report on any problems found. See
|
||||
Documentation/coccinelle.txt for more information.
|
||||
|
||||
Other kinds of portability errors are best found by compiling your code for
|
||||
other architectures. If you do not happen to have an S/390 system or a
|
||||
Blackfin development board handy, you can still perform the compilation
|
||||
|
|
@ -308,7 +320,9 @@ The first piece of documentation for any patch is its associated
|
|||
changelog. Log entries should describe the problem being solved, the form
|
||||
of the solution, the people who worked on the patch, any relevant
|
||||
effects on performance, and anything else that might be needed to
|
||||
understand the patch.
|
||||
understand the patch. Be sure that the changelog says *why* the patch is
|
||||
worth applying; a surprising number of developers fail to provide that
|
||||
information.
|
||||
|
||||
Any code which adds a new user-space interface - including new sysfs or
|
||||
/proc files - should include documentation of that interface which enables
|
||||
|
|
@ -372,7 +386,8 @@ which is broken by the change. For a widely-used function, this duty can
|
|||
lead to literally hundreds or thousands of changes - many of which are
|
||||
likely to conflict with work being done by other developers. Needless to
|
||||
say, this can be a large job, so it is best to be sure that the
|
||||
justification is solid.
|
||||
justification is solid. Note that the Coccinelle tool can help with
|
||||
wide-ranging API changes.
|
||||
|
||||
When making an incompatible API change, one should, whenever possible,
|
||||
ensure that code which has not been updated is caught by the compiler.
|
||||
|
|
|
|||
|
|
@ -60,12 +60,15 @@ even in the short term.
|
|||
|
||||
Patches must be prepared against a specific version of the kernel. As a
|
||||
general rule, a patch should be based on the current mainline as found in
|
||||
Linus's git tree. It may become necessary to make versions against -mm,
|
||||
linux-next, or a subsystem tree, though, to facilitate wider testing and
|
||||
review. Depending on the area of your patch and what is going on
|
||||
elsewhere, basing a patch against these other trees can require a
|
||||
significant amount of work resolving conflicts and dealing with API
|
||||
changes.
|
||||
Linus's git tree. When basing on mainline, start with a well-known release
|
||||
point - a stable or -rc release - rather than branching off the mainline at
|
||||
an arbitrary spot.
|
||||
|
||||
It may become necessary to make versions against -mm, linux-next, or a
|
||||
subsystem tree, though, to facilitate wider testing and review. Depending
|
||||
on the area of your patch and what is going on elsewhere, basing a patch
|
||||
against these other trees can require a significant amount of work
|
||||
resolving conflicts and dealing with API changes.
|
||||
|
||||
Only the most simple changes should be formatted as a single patch;
|
||||
everything else should be made as a logical series of changes. Splitting
|
||||
|
|
@ -100,7 +103,7 @@ rules of thumb, however, which can help considerably:
|
|||
result is a broken kernel, you will make life harder for developers and
|
||||
users who are engaging in the noble work of tracking down problems.
|
||||
|
||||
- Do not overdo it, though. One developer recently posted a set of edits
|
||||
- Do not overdo it, though. One developer once posted a set of edits
|
||||
to a single file as 500 separate patches - an act which did not make him
|
||||
the most popular person on the kernel mailing list. A single patch can
|
||||
be reasonably large as long as it still contains a single *logical*
|
||||
|
|
@ -162,7 +165,8 @@ To that end, the summary line should describe the effects of and motivation
|
|||
for the change as well as possible given the one-line constraint. The
|
||||
detailed description can then amplify on those topics and provide any
|
||||
needed additional information. If the patch fixes a bug, cite the commit
|
||||
which introduced the bug if possible. If a problem is associated with
|
||||
which introduced the bug if possible (and please provide both the commit ID
|
||||
and the title when citing commits). If a problem is associated with
|
||||
specific log or compiler output, include that output to help others
|
||||
searching for a solution to the same problem. If the change is meant to
|
||||
support other changes coming in later patch, say so. If internal APIs are
|
||||
|
|
@ -299,5 +303,5 @@ In general, the second and following parts of a multi-part patch should be
|
|||
sent as a reply to the first part so that they all thread together at the
|
||||
receiving end. Tools like git and quilt have commands to mail out a set of
|
||||
patches with the proper threading. If you have a long series, though, and
|
||||
are using git, please provide the --no-chain-reply-to option to avoid
|
||||
are using git, please stay away from the --chain-reply-to option to avoid
|
||||
creating exceptionally deep nesting.
|
||||
|
|
|
|||
|
|
@ -66,6 +66,11 @@ be easy to become blinded by your own solution to a problem to the point
|
|||
that you don't realize that something is fundamentally wrong or, perhaps,
|
||||
you're not even solving the right problem.
|
||||
|
||||
Andrew Morton has suggested that every review comment which does not result
|
||||
in a code change should result in an additional code comment instead; that
|
||||
can help future reviewers avoid the questions which came up the first time
|
||||
around.
|
||||
|
||||
One fatal mistake is to ignore review comments in the hope that they will
|
||||
go away. They will not go away. If you repost code without having
|
||||
responded to the comments you got the time before, you're likely to find
|
||||
|
|
@ -109,11 +114,10 @@ through the -mm tree.
|
|||
|
||||
Inclusion into a subsystem tree can bring a higher level of visibility to a
|
||||
patch. Now other developers working with that tree will get the patch by
|
||||
default. Subsystem trees typically feed into -mm and linux-next as well,
|
||||
making their contents visible to the development community as a whole. At
|
||||
this point, there's a good chance that you will get more comments from a
|
||||
new set of reviewers; these comments need to be answered as in the previous
|
||||
round.
|
||||
default. Subsystem trees typically feed linux-next as well, making their
|
||||
contents visible to the development community as a whole. At this point,
|
||||
there's a good chance that you will get more comments from a new set of
|
||||
reviewers; these comments need to be answered as in the previous round.
|
||||
|
||||
What may also happen at this point, depending on the nature of your patch,
|
||||
is that conflicts with work being done by others turn up. In the worst
|
||||
|
|
|
|||
|
|
@ -6,7 +6,7 @@ This document describes how to use the dynamic debug (ddebug) feature.
|
|||
|
||||
Dynamic debug is designed to allow you to dynamically enable/disable kernel
|
||||
code to obtain additional kernel information. Currently, if
|
||||
CONFIG_DYNAMIC_DEBUG is set, then all pr_debug()/dev_debug() calls can be
|
||||
CONFIG_DYNAMIC_DEBUG is set, then all pr_debug()/dev_dbg() calls can be
|
||||
dynamically enabled per-callsite.
|
||||
|
||||
Dynamic debug has even more useful features:
|
||||
|
|
@ -26,7 +26,7 @@ Dynamic debug has even more useful features:
|
|||
Controlling dynamic debug Behaviour
|
||||
===================================
|
||||
|
||||
The behaviour of pr_debug()/dev_debug()s are controlled via writing to a
|
||||
The behaviour of pr_debug()/dev_dbg()s are controlled via writing to a
|
||||
control file in the 'debugfs' filesystem. Thus, you must first mount the debugfs
|
||||
filesystem, in order to make use of this feature. Subsequently, we refer to the
|
||||
control file as: <debugfs>/dynamic_debug/control. For example, if you want to
|
||||
|
|
|
|||
Loading…
Reference in a new issue