FILES.CONF(5) BSD Reference Manual FILES.CONF(5)
files.conf - rules base for the config utility
The various files.* files located in the kernel source tree contain all
the necessary information needed by config(8) to parse a kernel confi-
guration 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.
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 enti-
ties, designed to make the driver code simpler. Usually, the top-most
devices are attached to the pseudo-device "mainbus", which is itself re-
ported 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 an SCSI controller device, or at
the logical atapiscsi(4) bus.
Some device attachments need to provide attachment information. For exam-
ple, 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 busses 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 autocon-
figure 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, given
define pci {[dev = -1], [function = -1]}
in the rules files, 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
The syntax
define attribute
defines a simple attribute, which can be later used to factorize code
dependencies. An attachment-like attribute will also require locators to
be specified, such as
define attribute {}
if no locators are necessary, or
define attribute {[locator1 = default1], [locator2 = default2]}
if locators are provided.
For simple device attachment, the syntax
define device {}
defines a simple device, with no locators. If locators are necessary,
they are specified as:
define device {[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 attri-
bute 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 device are defined as regular devices, except that they do not
need locators, and use a different keyword:
pseudo-device loop: inet
pseudo-device ksyms
define, respectively, the loopback network interface and the kernel sym-
bols pseudo-device.
Due to the tree structure of the device nodes, every device but the pseu-
do 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
which lists all the parent attributes a device may attach to. For exam-
ple, if a device is specified as:
device smartknob: bells, whistles
attach smartknob at brainbus
then a
smartknob* at brainbus?
configuration file line is valid, while a
smartknob* at dumbbus?
is not.
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
and will define more required attributes, depending on the kernel confi-
guration file's contents.
It is possible to include other rules files anywhere in a file, using the
"include" keyword:
include "dev/pci/files.pci"
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.
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
• the "option" lines, with the option name translated to lower-
case (for example, an "option INET" line will produce the
"inet" attribute).
• the device and pseudo-device names, except for "root".
Kernel source files are defined as:
file somewhere/somefile.c dependencies need-rules
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, the line
file netinet/ipsec_input.c (inet | inet6) & ipsec
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" at-
tributes, 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
substituting 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.
sys/arch/machine/conf/files.machine must also supply the following spe-
cial 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.
sys/arch/machine/conf/files.machine
Rules for architecture-dependent files, for the "machine" architec-
ture.
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.
contrib/gnu/emu387/fpemul/files.fpemul
Rules for the i386 GPL floating-point emulator.
sys/scsi/files.scsi
Rules for the common SCSI subsystem.
config(8)
MirBSD #10-current October 8, 2002 3