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The documentation grew one page at a time, so the tree follows the
history of who wrote what and not the shape of NuttX. Scheduling is
spread over three places, a driver page can sit above the subsystem
that owns it, and the front page lists everything at the same level.
That is a lot to face when all you want to know is where the scheduler
lives.
This change files every page under the code it describes. It is a move,
not a rewrite: outside the ten pages named below, every page keeps the
text that is already in master, and no page's text is deleted.
What it does:
* Groups the table of contents into nine chapters.
* Moves the OS subsystems under os/: scheduling, memory, drivers,
filesystem, networking, IPC, interrupts, libs, time.
* Renames the platform pages to the names the source tree uses, and
derives their tags from the tree instead of by hand.
* Splits guides/ by subject.
* Adds Documentation/redirects.py, with a rule for every page that left
its old path, so old URLs keep working. The redirect page also carries
a link's #anchor across to the new page.
Ten pages have text that is new or rewritten. Nine of them are the
landing page of a chapter, which has to exist for the new structure:
index the front page
os/index OS Design
os/scheduling/index Scheduling
os/interrupts/index Interrupts
os/ipc/index IPC
os/time/index Time and timers
about/index About
developing/index Developing NuttX
ReleaseNotes/index Release notes
The tenth is os/libs/libbuiltin, the only page here with technical
content: libs/libbuiltin/ had no page at all. Five SVG diagrams come
with these pages, hand-written XML with no editor metadata.
Nothing outside Documentation/ is touched.
How it was checked:
* Sphinx builds with -W: no warnings, and no document left outside a
toctree.
* A script, offered in the PR, proves the narrow claim this rests on.
For every page outside the ten named above it erases what a move
touches -- link target, path, tag line, toctree block, table border --
from the whole old text and the whole new text, and requires the two
to be byte for byte identical. It also requires every sentence of a
deleted page to turn up somewhere, and every page that left its old
path to have a redirect, from a URL that existed, to where its content
went. It exits non-zero and names the page if any of that is not true,
and it tests added pages too, so forgetting to declare one cannot make
it pass.
* An independent audit checked 133 factual claims on these ten pages
against the tree, one shell command per claim: 130 confirmed, 1
refuted and fixed here, 2 not checkable.
* tools/checkpatch.sh is clean over the range.
The diff is large because moving a page changes every link that points
to it. Most of it is pure renames, and board pages that gained one tag
line.
Assisted-by: Claude:claude-opus-5
97 lines
2.9 KiB
ReStructuredText
97 lines
2.9 KiB
ReStructuredText
.. _notifier_chain:
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==============
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Notifier Chain
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==============
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NuttX provides a callback list mechanism called *Notifier Chain*.
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Notifier chain is essentially a list of callbacks used at certain times,
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such as system asserting, powering off and restarting.
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**Notifier chain** is very much like the Linux notifier chains, except
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for some implementation differences.
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Classes of Notifier Chain
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=========================
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There are currently two different classes of notifier.
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Atomic notifier chains
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----------------------
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Atomic notifier chains: Chain callbacks run in interrupt/atomic context.
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In Nuttx, callouts are allowed to block(In Linux, callouts in atomic
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notifier chain are not allowed to block). One example of an Atomic notifier
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chain is turning off FPU when asserting.
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Blocking notifier chains
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------------------------
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Blocking notifier chains: Chain callbacks run in process context.
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Callouts are allowed to block. One example of a blocking notifier chain
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is when an orderly powering off is needed.
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Common Notifier Chain Interfaces
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================================
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Notifier Block Types
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--------------------
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- ``struct notifier_block``. Defines one notifier callback entry.
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Notifier Chain Interfaces
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-------------------------
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.. c:function:: void panic_notifier_chain_register(FAR struct notifier_block *nb)
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Add notifier to the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param nb: New entry in notifier chain.
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.. c:function:: void panic_notifier_chain_unregister(FAR struct notifier_block *nb)
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Remove notifier from the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param nh: Entry to remove from notifier chain.
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.. c:function:: void panic_notifier_call_chain(unsigned long action, FAR void *data)
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Call functions in the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param action: Value passed unmodified to notifier function.
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:param data: Pointer passed unmodified to notifier function.
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.. c:function:: void register_reboot_notifier(FAR struct notifier_block *nb)
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Add notifier to the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param nb: New entry in notifier chain.
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.. c:function:: void unregister_reboot_notifier(FAR struct notifier_block *nb)
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Remove notifier from the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param nh: Entry to remove from notifier chain.
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.. c:function:: void reboot_notifier_call_chain(unsigned long action, FAR void *data)
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Call functions in the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param action: Value passed unmodified to notifier function.
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:param data: Pointer passed unmodified to notifier function.
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