Tribblix: manual page: Intro.9

INTRO(9) Kernel Concepts INTRO(9)

NAME

Intro - introduction to kernel concepts, device drivers, functions, and
structures

DESCRIPTION

Section 9 of the manual is documentation for concepts in the broader
kernel, including writing device drivers. The manual is organized into
different sections, each of which focuses on a particular area such as
chapter 9E which covers device driver entry points. The following
chapters of section 9 exist:

Section 9
The base section 9 (no chapter suffix) contains various high-
level concepts about the kernel. In addition to this page,
there are manuals that cover:

iports, phymaps, and tgtmaps
iport(9) discusses the design of abstractions that are
used for host bus adapter (HBA) drivers to aid in the
enumeration of devices.

vmem vmem(9) discusses the design of the virtual memory
allocator that is used throughout the system.

Section 9E
Section 9E, driver entry points, describes the interfaces that
a loadable kernel module and device driver need to implement to
interface with the broader kernel. There are discussions of
specific frameworks for different classes of drivers, such as
mac(9E) for networking device drivers, discussions of specific
functions that a given device might implement like open(9E)
which correspond to performing a traditional operation on the
device, and required entry points for all modules like
_init(9E).

Intro(9E) provides an overview of loadable kernel modules,
device drivers, and which function families are used for which
types of devices.

Section 9F
Section 9F, kernel functions, describes the various kernel
functions that are available. The majority of these functions
are part of the device driver interface and have API and ABI
guarantees associated with them. Entry points run the gamut
from dealing with memory allocation, to common data structures,
to device driver frameworks (e.g. functions specific to
Networking, USB, SCSI, etc. drivers), to common C functions
around strings, atomics, and memory copying.

Intro(9F) discusses the different groups of functions that are
available and how they are often used.

Section 9P
Section 9P, properties, are used to document various properties
that a device driver may set on themselves. These properties
are generally used in tandem with a driver's driver.conf(5) or
set while the driver is executing.

Section 9S
Section 9S, structures, describes various structures that are
filled out, their members, and their meanings that are used
throughout the kernel. This includes various types like the
mblk_t which is used to transfer data in the networking and USB
stacks, the uio_t which is used to describe an I/O request, and
the cb_ops which all character device drivers fill out to
indicate which operations they support.

Intro(9S) describes the organization of the different structure
types that exist. If exploring a subsystem, it is generally
better to start with the corresponding 9E and 9F discussions
which often have more context for how these structures are
used.

Throughout the manuals you may see reference to the term "DDI" which is
the Device Driver Interface, which represents the committed interfaces
that the operating system exports for such purposes. Note, not
everything documented is classified as a committed interface. Some
uncommitted interfaces are documented to aid developers. In addition
to these manuals, there is additional documentation in the form of
various books available at https://illumos.org/books. In particular,
the following books can be useful for writing software and debugging:

Dynamic Tracing Guide
This introduces and discusses how to use DTrace, the dynamic
tracing facility built into the operating system. DTrace is
used with the dtrace(8) utility.

Modular Debugger Guide
This introduces and discusses how to use the modular debugger,
which provides the ability to debug not only user processes,
but both the kernel and crash dumps. To start debugging the
kernel, use the -k flag to mdb(1).

Writing Device Drivers
This introduces how to write device drivers in the system and
provides additional background and more guided tours of various
types of devices and concepts such as DMA allocation.

NAME

DESCRIPTION

SEE ALSO