FILES.CONF(5) OpenBSD Programmer's Manual FILES.CONF(5)NAMEfiles.conf - rules base for the config utility
DESCRIPTION
The various files.* files located in the kernel source tree contain all
the necessary information needed by config(8) to parse a kernel
configuration file and determine the list of files to compile.
The files.* rules base are simple, human-readable, text files. Empty
lines, as well as text prefixed by the `#' character, are ignored.
DEVICE TREE CONCEPT
The OpenBSD kernel ``sees'' the various devices as a hierarchical tree,
where the various devices ``attach'' to parent entities, which can either
be physical devices themselves (such as a computer bus), or logical
entities, designed to make the driver code simpler. Usually, the top-
most devices are attached to the pseudo-device ``mainbus'', which is
itself reported as attached to a fictitious ``root'' node. There is no
restriction on the ``children'' a device node may have; some device
drivers can attach themselves to different kinds of parent devices. For
example, the logical scsibus(4) device can either attach at a SCSI
controller device, or at the logical atapiscsi(4) bus.
LOCATORS
Some device attachments need to provide attachment information. For
example, an isa(4) device will use a range of I/O ports, one or more DMA
channels, and one interrupt vector. This attachment information is known
as the ``locators'' for the device. Most of the buses support default
values for unspecified locators, for devices that either do not require
them (such as isa(4) cards not using interrupts), or which can
autoconfigure themselves (such as pci(4) devices).
Attachment lines in the kernel configuration file must match the locators
of the device they are attaching to. For example:
define pci {[dev = -1], [function = -1]}
With the rule above, the following kernel configuration lines are valid:
pciknob0 at pci? dev 2 function 42 # use fixed values
pciknob* at pci? dev ? function ? # use default values
pciknob* at pci? # use default locators
But the following are not:
pciknob* at pci? trick ? treat ? # unknown locators
pciknob* at pci? dev ? function ? usefulness ? # unknown locators
ATTRIBUTES
The following syntax defines a simple attribute, which can be later used
to factorize code dependencies:
define attribute
An attachment-like attribute will also require locators to be specified.
If no locators are necessary:
define attribute {}
If locators are provided:
define attribute {[locator1 = default1], [locator2 = default2]}
DEVICES
For simple device attachment, the following syntax defines a simple
device, with no locators:
device devicename {}
If locators are necessary, they are specified as:
device devicename {[locator1 = default1], [locator2 = default2]}
A device can also reference an attribute with locators. This is in fact
a dependency rule. For example, sys/conf/files defines the following
attribute for SCSI controllers:
define scsi {} # no locators
And SCSI drivers can then be defined as:
device scsictrl: scsi
A device may depend on as many attributes as necessary:
device complexdev: simpledev, otherdev, specialattribute
PSEUDO DEVICES
Pseudo devices are defined as regular devices, except that they do not
need locators, and use a different keyword:
pseudo-device loop: inet
pseudo-device ksyms
The rules above define, respectively, the loopback network interface and
the kernel symbols pseudo-device.
DEVICE ATTACHMENT RULES
Due to the tree structure of the device nodes, every device but the
pseudo devices need to attach to some parent node. A device driver has
to specify to which parents it can attach, with the following syntax:
attach device at parent, parent2, parent3
The rule above lists all the parent attributes a device may attach to.
For example, given the following:
device smartknob: bells, whistles
attach smartknob at brainbus
The following configuration line is then valid:
smartknob* at brainbus?
Whilst the following is not:
smartknob* at dumbbus?
If a device supports attachments to multiple parents, using different
``glue'' routines every time, the following syntax specifies the details:
attach device at parent with device_parent_glue
attach device at parent2 with device_parent2_glue
This will define more required attributes, depending on the kernel
configuration file's contents.
RULE FILE INCLUSION
It is possible to include other rules files anywhere in a file, using the
``include'' keyword:
include "dev/pci/files.pci"
The above rule will include the rules for machine-independent PCI code.
The files sys/arch/machine/conf/files.machine, for every ``machine''
listed in the machine line in the kernel configuration file, as well as
sys/conf/files, are always processed, and do not need to be included.
ATTRIBUTE REQUIREMENTS
The kernel configuration file description passed to config(8) lists
several compilation options, as well as several device definitions. From
this list, config(8) will build a list of required attributes, which are:
o The ``option'' lines, with the option name translated to
lowercase (for example, an ``option INET'' line will produce
the ``inet'' attribute).
o The device and pseudo-device names, except for ``root''.
KERNEL FILE LIST
Kernel source files are defined as:
file file-list dependencies need-rules
``file-list'' typically only specifies a single filename. If instead it
contains a list of filenames separated by the `|' character, config(8)
will select the first file from the list which exists. If
``${MACHINE_ARCH}'' or ``${MACHINE}'' is found in the filename, it will
be substituted with the relevant base architecture name.
If the ``dependencies'' part is empty, the file will always be compiled
in. This is the case for the core kernel files. Otherwise, the file
will only be added to the list if the dependencies are met. Dependencies
are based upon attributes and device names. Multiple dependencies can be
written using the ``|'' and ``&'' operators. For example:
file netinet/ipsec_input.c (inet | inet6) & ipsec
The above rule teaches config(8) to only add sys/netinet/ipsec_input.c to
the filelist if the ``ipsec'' attribute, and at least one of the ``inet''
and ``inet6'' attributes, are required.
The ``need'' rules can be empty, or one of the following keywords:
needs-flag Create an attribute header file, defining whether or not
this attribute is compiled in.
needs-count Create an attribute header file, defining how many instances
of this attribute are to be compiled in. This rule is
mostly used for pseudo-devices.
The ``attribute header files'' are simple C header files created in the
kernel compilation directory, with the name attribute.h and containing
the following line:
#define NATTRIBUTE 0
This would substitute the attribute name and its uppercase form, prefixed
with the letter ``N'', to ``attribute'' and ``NATTRIBUTE'', respectively.
For a ``needs-flag'' rule, the value on the ``#define'' line is either 1
if the attribute is required, or 0 if it is not required. For a
``needs-count'' rule, the value is the number of device instances
required, or 0 if the device is not required.
Attribute files are created for every attribute listed with a ``need''
rule, even if it is never referenced from the kernel configuration file.
MISCELLANEOUS ITEMS
sys/arch/machine/conf/files.machine must also supply the following
special commands:
maxpartitions Defines how many partitions are available on disk block
devices, usually 16. This value is used by config(8) to
set up various device information structures.
maxusers Defines the bounds, and the default value, for the
``maxusers'' parameter in the kernel configuration file.
The usual values are 2 8 64 ; config(8) will report an
error if the ``maxusers parameter'' in the kernel
configuration file does not fit in the specified range.
FILES
sys/arch/machine/conf/files.machine
Rules for architecture-dependent files, for the ``machine''
architecture.
sys/compat/emul/files.emul
Rules for the ``emul'' operating system or subsystem emulation.
sys/dev/class/files.class
Rules for the ``class'' class of devices.
sys/scsi/files.scsi
Rules for the common SCSI subsystem.
SEE ALSOconfig(8)OpenBSD 4.9 April 26, 2009 OpenBSD 4.9
