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.\"     from: @(#)config.8	8.2 (Berkeley) 4/19/94
.\"
.Dd $Mdocdate: October 7 2017 $
.Dt CONFIG 8
.Os
.Sh NAME
.Nm config
.Nd build kernel compilation directories or modify a kernel
.Sh SYNOPSIS
.Nm config
.Op Fl p
.Op Fl b Ar builddir
.Op Fl s Ar srcdir
.Op Ar config-file
.Nm config
.Op Fl u
.Op Fl f | o Ar outfile
.Fl e
.Ar infile
.Sh DESCRIPTION
In the first synopsis form, the
.Nm
program creates a kernel build directory from the kernel configuration file
specified by
.Ar config-file .
.Pp
In the second synopsis form,
.Nm
allows editing of the kernel binary specified by
.Ar infile .
Devices may be enabled, disabled, or modified without recompiling,
by editing the kernel executable.
Similarly, the same editing can be done at boot-time,
using the in-kernel editor,
as described in
.Xr boot_config 8 .
.Pp
For kernel building, the options are as follows:
.Bl -tag -width Ds
.It Fl b Ar builddir
Create the build directory in the path specified by
.Ar builddir
instead of the default
.Pa ../compile/SYSTEMNAME .
.It Fl p
Configure for a system that includes profiling code; see
.Xr kgmon 8
and
.Xr gprof 1 .
When this option is specified,
.Nm
acts as if the lines
.Dq makeoptions PROF="-pg"
and
.Dq option GPROF
appeared in the specified kernel configuration file.
In addition,
.Dq .PROF
is appended to the default compilation directory name.
.Pp
The
.Fl p
flag is expected to be used for
.Dq one-shot
profiles of existing systems; for regular profiling, it is probably wiser to
make a separate configuration containing the makeoptions line.
.It Fl s Ar srcdir
Use
.Ar srcdir
as the top-level kernel source directory instead of the default (four
directories above the build directory).
.El
.Pp
For kernel modification, the options are as follows:
.Bl -tag -width Ds
.It Fl e
Allows the modification of kernel device configuration (see
.Xr 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
.Sx KERNEL MODIFICATION
below for more details.
.It Fl f
Overwrite the
.Ar infile
kernel binary with the modified kernel.
Otherwise,
.Fl o
should be given to specify an alternate output file.
.It Fl o Ar outfile
Write the modified kernel to
.Ar outfile .
.It Fl u
Check to see if the kernel configuration was modified at boot-time
(i.e.\&
.Cm boot -c
was used).
If so, compare the running kernel with the kernel to be edited
.Pq Ar infile .
If they seem to be the same, apply all configuration changes performed at
boot.
Using this option requires read access to
.Pa /dev/mem ,
which may be restricted based upon the value of the
.Ar kern.allowkmem
.Xr sysctl 8 .
.El
.Sh KERNEL BUILDING
The output of
.Nm
consists of a number of files, principally
.Pa ioconf.c
(a description of I/O devices that may be attached to the system)
and a
.Pa Makefile ,
used by
.Xr make 1
when building the kernel.
.Pp
If
.Nm
stops due to errors, the problems reported should be corrected and
.Nm
should be run again.
.Nm
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.
.Pp
If
.Ar config-file
is not specified,
.Nm
uses the current directory as the build directory, and looks in it for
a file called
.Pa CONFIG .
If
.Nm
is run this way, the location of the top-level kernel source
directory must be specified using the
.Fl s
option or by using the
.Dq Li source
directive at the beginning of the system configuration file.
.Pp
The configuration files consists of various statements which
include the following:
.Bl -tag -offset indent -width indent
.It Ic machine Ar var
Required.
Specifies the machine architecture.
.It Ic include Ar file
Include another configuration file.
.It Ic option Ar name
Set a kernel option.
Kernel options may take either the form
.Ar NAME
or the form
.Ar NAME Ns = Ns Ar value .
These options are passed to the compiler with the
.Fl D
flag.
.It Ic rmoption Ar name
Delete a previously set option.
This is useful when including another kernel configuration file.
A typical use is to include the
.Va GENERIC
kernel provided with each release and remove options that are
unwanted, thus allowing for automatic inclusion of new device
drivers.
.It Ic maxusers Ar 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 provided in the last instance will be used, and
warnings will be printed for each duplicate value.
This is convenient when used with the
.Va include
directive.
.It Xo Ic config Cm bsd root on Ar dev
.Op Cm swap on Ar dev Op Cm and Ar dev ...
.Op Cm dumps on Ar dev
.Xc
Required.
Specifies the swap and dump devices which the system should use.
.It Ic config Cm bsd swap generic
Otherwise, if generic is specified, the system follows generic routines to
decide what should happen.
.El
.Pp
To debug kernels and their crash dumps with gdb, add
.Dq makeoptions DEBUG="-g"
to the kernel configuration file.
Refer to
.Xr options 4
for further details.
.Pp
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
.Xr files.conf 5
for the
.Nm
rules base.
.Sh KERNEL MODIFICATION
When
.Fl 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 running kernel and can be written to
a new kernel binary so changes are preserved during subsequent system restarts.
.Pp
When invoked, the kernel identification is first shown.
.Bd -literal -offset indent
# config -e -o bsd.new /bsd
OpenBSD 5.3-current (GENERIC.MP) #91: Mon Mar 25 16:43:17 MDT 2013
    deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC.MP
Enter 'help' for information
ukc\*(Gt
.Ed
.Pp
One or more warnings may be printed before the
.Li ukc\*(Gt
prompt.
.Bd -literal -offset indent
warning: no output file specified
.Ed
.Pp
Neither the
.Fl f
nor
.Fl o
option has been specified.
Changes will be ignored.
.Bd -literal -offset indent
WARNING kernel mismatch. -u ignored.
WARNING the running kernel version:
.Ed
.Pp
.Nm
does not believe the running kernel is the same as the
.Ar infile
specified.
Since the log of changes (from
.Cm boot -c )
in the running kernel is kernel-specific, the
.Fl u
option is ignored.
.Pp
The commands are as follows:
.Bl -tag -width "disable attr val | devno | dev"
.It Ic add Ar dev
Add a device through copying another.
.It Ic base Cm 8 | 10 | 16
Change the base of numbers displayed and entered.
.It Ic bufcachepercent Op Ar number
Change the BUFCACHEPERCENT value.
Without arguments, displays its current value.
.It Ic change Ar devno | dev
Modify one or more devices.
.It Ic disable Ar attr val | devno | dev
Disable one or more devices.
.It Ic enable Ar attr val | devno | dev
Enable one or more devices.
.It Ic exit
Exit without saving changes.
.It Ic find Ar devno | dev
Find one or more devices.
.It Ic help
Give a short summary of all commands and their arguments.
.It Ic lines Op Ar count
Set the number of rows per page.
.It Ic list
Show all known devices, a screen at a time.
.It Ic nkmempg Op Ar number
Change the NKMEMPAGES value.
Without arguments, displays its current value.
.It Ic quit
Exit and save changes.
.It Ic show Op Ar attr Op Ar val
Show all devices for which attribute
.Ar attr
has the value
.Ar val .
.It Ic timezone Op Ar minuteswest Op Ar dst
Change the
.Va tz
timezone structure.
.Va minuteswest
is the number of minutes west of GMT and
.Va dst
is non-zero if Daylight Saving Time is in effect.
Without arguments, displays its current value.
.El
.Sh EXAMPLES (kernel building)
Note:
The standard
.Ox
kernel configuration
(GENERIC or GENERIC.MP)
is suitable for most purposes.
Use of an alternative kernel configuration is not recommended.
A custom kernel is built in the following way.
.Pp
To compile a kernel from a non-writable media (such as a CD-ROM)
mounted on
.Pa /usr/src ,
do the following:
.Bd -literal -offset indent
# cd /somedir
# cp /usr/src/sys/arch/somearch/conf/SOMEFILE .
# vi SOMEFILE	(to make any changes)
# config -s /usr/src/sys -b . SOMEFILE
# make
.Ed
.Pp
To compile a kernel inside a writable source tree, do the following:
.Bd -literal -offset indent
# cd /usr/src/sys/arch/somearch/conf
# vi SOMEFILE	(to make any changes)
# config SOMEFILE
# cd ../compile/SOMEFILE
# make
.Ed
.Pp
In the examples above,
.Ar somedir
is a writable directory,
.Ar somearch
is the architecture (e.g. i386),
and
.Ar SOMEFILE
should be a name indicative of a particular configuration (often
that of the hostname).
.Nm config
will warn if a
.Dq make clean
is required.
.Pp
The new kernel, called
.Pa bsd ,
can be copied to
.Pa /bsd
and the system will boot it next time.
Most people save their backup kernels as
.Pa /bsd.1 ,
.Pa /bsd.2 ,
etc.
.Sh EXAMPLES (kernel modification)
The Ethernet card is not detected at boot because the kernel configuration
does not match the physical hardware configuration,
e.g. wrong IRQ in OpenBSD/i386.
The Ethernet card is supposed to use the
.Xr ne 4
driver.
.Bd -literal
.No ukc\*(Gt Ic 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\*(Gt
.Ed
.Pp
ne1 seems to match the configuration except it uses IRQ 10 instead of IRQ 5.
So the irq on ne1 should be changed via the
.Ic change
command.
The device can be specified by either name or number.
.Bd -literal
.No ukc\*(Gt Ic change ne1
25 ne1 at isa0 port 0x300 size 0 iomem -1 iosiz 0 irq 10 drq -1 drq2 -1
.No change (y/n) \&? Ic y
.No port [0x300] \&?
.No size [0] \&?
.No iomem [-1] \&?
.No iosiz [0] \&?
.No irq [10] \&? Ic 5
.No drq [-1] \&?
.No drq2 [-1] \&?
.No 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\*(Gt
.Ed
.Pp
It's also possible to disable all devices with a common attribute.
For example:
.Bd -literal
.No ukc\*(Gt Ic disable port 0x300
 25 ne1 disabled
 72 we1 disabled
 75 el0 disabled
 77 ie1 disabled
.Ed
.Pp
The
.Cm show
command is useful for finding which devices have a certain attribute.
It can also be used to find those devices with a particular value for
an attribute.
.Bd -literal
.No ukc\*(Gt Ic 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
.No ukc\*(Gt Ic 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\*(Gt
.Ed
.Pp
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 renumbered.
.Bd -literal
.No ukc\*(Gt Ic 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
.No ukc\*(Gt Ic add ep1
.No "Clone Device (DevNo, 'q' or '\&?') \&?" Ic 13
.No "Insert before Device (DevNo, 'q' or '\&?')" Ic 14
 14 ep1 at pci* dev -1 function -1
.No ukc\*(Gt Ic change 14
 14 ep1 at pci* dev -1 function -1
.No change (y/n) \&? Ic y
.No dev [-1] \&? Ic 14
.No function [-1] \&?
.No flags [0] \&? Ic 18
 14 ep1 changed
 14 ep1 at pci* dev 14 function -1 flags 0x12
ukc\*(Gt
.Ed
.Pp
When done, exit the program with the
.Ic quit
or
.Ic exit
commands.
.Ic exit
will ignore any changes while
.Ic quit
writes the changes to
.Ar outfile
(if
.Fl o
or
.Fl f
was given, else ignore changes).
.Bd -literal
.No ukc\*(Gt Ic quit
.Ed
.Sh SEE ALSO
.Xr options 4 ,
.Xr files.conf 5 ,
.Xr boot.conf 8 ,
.Xr boot_config 8
.Pp
The SYNOPSIS portion of each device in section 4 of the manual.
.Rs
.%T "Building 4.4 BSD Systems with Config"
.Re
.Sh HISTORY
The
.Nm
program appeared in
.Bx 4.1
and was completely revised in
.Bx 4.4 .
The
.Fl e
option appeared in
.Ox 2.6 .
.Sh BUGS
Included files should start with an empty line or comment.