CONFIG(8) BSD System Manager's Manual CONFIG(8)
config - build kernel compilation directories or modify a kernel
config [-b builddir] [-p] [-s srcdir] [config-file]
config -e [-f | -o outfile] [-u] infile
In the first synopsis form, the config program creates a kernel build
directory from the kernel configuration file specified by config-file. In
the second synopsis form, config allows editing of the kernel binary
specified by infile.
Furthermore, devices may be enabled, disabled, or modified without recom-
piling, by editing the kernel executable using the -e option. Similarly,
you can do the same editing at boot-time, using the in-kernel editor, as
described in boot_config(8).
config is most commonly invoked from the directory containing OpenBSD
kernel configuration files (i.e., /usr/src/sys/arch/i386/conf for i386
machines). For instance, the following steps would be followed to config-
ure and compile a new GENERIC kernel (assuming a complete kernel source
tree is available in /usr/src/sys):
# cd /usr/src/sys/arch/i386/conf
# config ./GENERIC
# cd ../compile/GENERIC
# make depend && make
Replace "i386" with the appropriate architecture name.
For kernel building, the options are as follows:
-b builddir
Create the build directory in the path specified by builddir in-
stead of the default ../compile/SYSTEMNAME.
-p Configure for a system that includes profiling code; see kgmon(8)
and gprof(1). When this option is specified, config acts as if
the lines "makeoptions PROF="-pg"" and "options GPROF" appeared
in the specified kernel configuration file. In addition, ".PROF"
is appended to the default compilation directory name.
The -p flag is expected to be used for "one-shot" profiles of ex-
isting systems; for regular profiling, it is probably wiser to
make a separate configuration containing the makeoptions line.
-s srcdir
Use srcdir as the top-level kernel source directory instead of
the default (four directories above the build directory).
For kernel modification, the options are as follows:
-e Allows the modification of kernel device configuration (see
boot_config(8)). Temporary changes can be made to the running
kernel's configuration or a new kernel binary may be written for
permanent changes between system reboots. See the section Kernel
modification below for more details.
-f Overwrite the infile kernel binary with the modified kernel. Oth-
erwise, -o should be given to specify an alternate output file.
-o outfile
Write the modified kernel to outfile.
-u Check to see if the kernel configuration was modified at boot-
time (i.e., boot -c was used). If so, compare the running kernel
with the kernel to be edited (infile). If they seem to be the
same, apply all configuration changes performed at boot.
The old -g flag is deprecated and no longer supported. Instead, add
"makeoptions DEBUG="-g"" to the kernel configuration file, along with
(typically) "options KGDB".
The output of config consists of a number of files, principally ioconf.c
(a description of I/O devices that may be attached to the system) and a
Makefile, used by make(1) when building the kernel.
After running config it is wise to run "make depend" in the new build
directory. config prints a reminder of this when it completes.
If config stops due to errors, the problems reported should be corrected
and config should be run again. config attempts to avoid changing the
compilation directory if there are configuration errors, but this code is
not well-tested and some problems (such as running out of disk space) are
unrecoverable.
If config-file is not specified, config uses the current directory as the
build directory, and looks in it for a file called CONFIG. If you run
config this way, you must specify the location of the top-level kernel
source directory using the -s option or by using the "source" directive
at the beginning of the system configuration file.
The configuration files consists of various statements which include the
following:
machine var
Required. Specifies the machine architecture.
include file
Include another configuration file.
option name
Set a kernel option. Kernel options may take either the
form NAME or the form NAME=value. These options are passed
to the compiler with the -D flag.
rmoption name
Delete a previously set option. This is useful when includ-
ing another kernel configuration file. A typical use is to
include the GENERIC kernel provided with each release and
remove options that are unwanted, thus allowing for au-
tomatic inclusion of new device drivers.
maxusers number
Required. Used to size various system tables and maximum
operating conditions in an approximate fashion. Multiple
instances of this keyword may be specified. The number pro-
vided in the last instance will be used, and warnings will
be printed for each duplicate value. This is convenient
when used with the include directive.
config bsd root on dev [swap on dev [and dev ...]] [dumps on dev
[and dev ...]]
Required. Specifies the swap and dump devices which the
system should use.
config bsd swap generic
Otherwise, if generic is specified, the system follows gen-
eric routines to decide what should happen.
Many other statements exist, and the file format is fairly rich; for more
information see the various configuration files included in the system,
as well as files.conf(5) for the config rules base.
When -e is specified, device parameters that are normally hard-coded into
the kernel may be changed. This is useful to avoid the need for kernel
recompilation or rebooting. Modifications are made to the currently run-
ning kernel and can be written to a new kernel binary so changes are
preserved during subsequent system restarts.
When invoked, the kernel identification is first shown.
# config -e -o bsd.new /bsd
OpenBSD 2.6-beta (GENERIC.rz0) #0: Mon Oct 4 03:57:22 MEST 1999
root@winona:/usr/src/sys/arch/pmax/compile/GENERIC.rz0
Enter 'help' for information
ukc>
One or more warnings may be printed before the ukc> prompt.
warning: no output file specified
Neither the -f nor -o option has been specified. Changes will be ignored.
WARNING this kernel doesn't contain all information needed!
WARNING the commands add and change might not work.
The kernel is too old (pre OpenBSD 2.6) and cannot support all of the
functionality needed by the -e option.
WARNING kernel mismatch. -u ignored.
WARNING the running kernel version:
config does not believe the running kernel is the same as the infile
specified. Since the log of changes (from boot -c) in the running kernel
is kernel-specific, the -u option is ignored.
The commands are as follows:
add dev Add a device through copying another.
base 8 | 10 | 16 Change the base of numbers displayed and
entered, e.g., I/O addresses in a VAXen
are octal.
change devno | dev Modify one or more devices.
disable attr val | devno | dev Disable one or more devices.
enable attr val | devno | dev Enable one or more devices.
exit Exit without saving changes.
find devno | dev Find one or more devices.
help Give a short summary of all commands and
their arguments.
list Show all known devices, a screen at a
time.
lines [count] Set the number of rows per page. 0 dis-
ables paging.
quit Exit and save changes.
show [attr [val]] Show all devices for which attribute attr
has the value val.
timezone [minuteswest [dst]] Change the tz timezone structure. Without
arguments, displays its current value.
cachepct [number] Change the BUFCACHEPERCENT value. Without
arguments, displays its current value.
nkmempg [number] Change the NKMEMPAGES value. Without ar-
guments, displays its current value.
shmseg [number] Change the SHMSEG value. Without argu-
ments, displays its current value.
shmmaxpgs [number] Change the SHMMAXPGS value. Without argu-
ments, displays its current value.
EXAMPLES (First synopsis)
A custom kernel is built in the following way.
To compile your own kernel from a non-writable media (such as a CD-ROM)
mounted on /usr/src, do the following:
# cd /somedir
# cp /usr/src/sys/arch/somearch/conf/SOMEFILE .
# vi SOMEFILE (to make any changes)
# config -s /usr/src/sys -b . SOMEFILE
# make
To compile a kernel inside a writable source tree, do the following:
# cd /usr/src/sys/arch/somearch/conf
# vi SOMEFILE (to make any changes)
# config SOMEFILE
# cd ../compile/SOMEFILE
# make
where somedir is a writable directory, somearch is the architecture
(e.g., i386), and SOMEFILE should be a name indicative of a particular
configuration (often that of the hostname). config will warn you if a
"make clean" is required; you can also do a "make depend" so that you
will have dependencies there the next time you do a compile.
After either of these two methods, you can place the new kernel (called
bsd) in / (i.e., /bsd) and the system will boot it next time. Most people
save their backup kernels as /bsd.1, /bsd.2, etc.
EXAMPLES (Second synopsis)
The Ethernet card is not detected at boot because the kernel configura-
tion does not match the physical hardware configuration, e.g., wrong IRQ
in OpenBSD/i386. The Ethernet card is supposed to use the ne(4) driver.
ukc> find ne
24 ne0 at isa0 port 0x240 size 0 iomem 0xd8000 iosiz 0 irq 9 drq -1 drq2 -1 flags 0x0
25 ne1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
26 ne* at isapnp0 port -1 size 0 iomem -1 iosiz 0 irq -1 drq -1 flags 0x0
27 ne* at pci* dev -1 function -1 flags 0x0
28 ne* at pcmcia* function -1 irq -1 flags 0x0
ukc>
ne1 seems to match the configuration except it uses IRQ 5 instead of IRQ
10. So the irq on ne1 should be changed via the change command. The dev-
ice can be specified by either name or number.
ukc> change ne1
25 ne1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1
change (y/n) ? y
port [0x300] ?
size [0] ?
iomem [-1] ?
iosiz [0] ?
irq [10] ? 5
drq [-1] ?
drq2 [-1] ?
flags [0] ?
25 ne1 changed
25 ne1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 5 drq -1 drq2 -1 flags 0x0
ukc>
Another case is a mistakenly detected non-existing device instead of
another device at the probed location. One known case is the Mitsumi CD-
ROM in OpenBSD/i386. The simplest thing to solve that problem is to dis-
able mcd0.
ukc> find mcd0
29 mcd0 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
ukc> disable mcd0
29 mcd0 disabled
ukc> find 29
29 mcd0 at isa0 disable port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
It's also possible to disable all devices with a common attribute. e.g.,
ukc> disable port 0x300
25 ne1 disabled
29 mcd0 already disabled
72 we1 disabled
75 el0 disabled
77 ie1 disabled
The show command is useful for finding which devices have a certain at-
tribute. It can also be used to find those devices with a particular
value for an attribute.
ukc> show slot
2 ahc* at eisa0 slot -1
10 uha* at eisa0 slot -1
12 ep0 at eisa0 slot -1
17 ep* at eisa0 slot -1
102 ahb* at eisa0 slot -1
103 fea* at eisa0 slot -1
ukc> show port 0x300
25 ne1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
72 we1 at isa0 port 0x300 size 0 iomem 0xcc000 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
75 el0 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 9 drq -1 drq2 -1 flags 0x0
77 ie1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1 flags 0x0
ukc>
It is possible to add new devices, but only devices that were linked into
the kernel. If a new device is added, following devices will be renum-
bered.
ukc> find ep
11 ep0 at isa0 port -1 size 0 iomem -1 iosiz 0 irq -1 drq -1 drq2 -1 flags 0x0
12 ep0 at eisa0 slot -1 flags 0x0
13 ep0 at pci* dev -1 function -1 flags 0x0
14 ep* at isapnp0 port -1 size 0 iomem -1 iosiz 0 irq -1 drq -1 flags 0x0
15 ep* at isa0 port -1 size 0 iomem -1 iosiz 0 irq -1 drq -1 drq2 -1 flags 0x0
16 ep* at eisa0 slot -1 flags 0x0
17 ep* at pci* dev -1 function -1 flags 0x0
18 ep* at pcmcia* dev -1 irq -1 flags 0x0
ukc> add ep1
Clone Device (DevNo, 'q' or '?') ? 13
Insert before Device (DevNo, 'q' or '?') 14
14 ep1 at pci* dev -1 function -1
ukc> change 14
14 ep1 at pci* dev -1 function -1
change (y/n) ? y
dev [-1] ? 14
function [-1] ?
flags [0] ? 18
14 ep1 changed
14 ep1 at pci* dev 14 function -1 flags 0x12
ukc>
When done, exit the program with the quit or exit commands. exit will ig-
nore any changes while quit writes the changes to outfile (if -o or -f
was given, else ignore changes).
ukc> quit
options(4), files.conf(5), boot_config(8)
The SYNOPSIS portion of each device in section 4 of the manual.
Building 4.4 BSD Systems with Config.
The config program appeared in 4.1BSD. It was completely revised in
4.4BSD. The -e option appeared in OpenBSD 2.6.
MirBSD #10-current October 15, 1999 5