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BOOT_CONFIG(8)          OpenBSD System Manager's Manual         BOOT_CONFIG(8)

NAME
     boot_config - how to change kernel configuration at boot

DESCRIPTION
     BOOT_CONFIG is a kernel option that makes it possible to change the con-
     figuration at boot time.  The same interface is available from userland,
     using the -e argument to config(8).

     The boot time configuration is invoked by the -c option when OpenBSD
     prompts for a kernel to boot:

     >> OpenBSD BOOT 640/31744 k [1.29]
     use ? for file list, or carriage return for defaults
     use hd(1,a)/bsd to boot sd0 when sd0 is also installed
     Boot: [[[wd(0,a)]/bsd][-abcdrs]]: -c
     Booting...
     avail mem = 28188672
     using 430 buffers containing 1761280 bytes of memory
     User Kernel Config
     UKC>

     Changes made can be saved for the next reboot, by using config(8).

COMMANDS
     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 devno | dev  Disable one or more devices.

     enable devno | dev   Enable one or more devices.

     exit                 Continue boot.

     find devno | dev     Find one or more devices.

     help                 Give a short summary of all commands and their argu-
                          ments.

     list                 Show all known devices, a screen at a time.

     lines [count]        Set the number of rows per page.

     quit                 Continue boot.

     show [attr [val]]    Show all devices for which attribute attr has the
                          value val.

     timezone [minuteswest [dst]]
                          Change the tz timezone structure.  Without argu-
                          ments, displays its current value.

     verbose              Toggle the autoconfig verbose variable.

EXAMPLES
     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 de-
     vice 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 flags 0x0
     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 an-
     other 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

     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 flags 0x0
      10 uha* at eisa0 slot -1 flags 0x0
      12 ep0 at eisa0 slot -1 flags 0x0
      17 ep* at eisa0 slot -1 flags 0x0
     102 ahb* at eisa0 slot -1 flags 0x0
     103 fea* at eisa0 slot -1 flags 0x0
     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 configuration is completed, booting can proceed by issuing the quit
     or exit commands.

     UKC> quit
     Continuing...
     mainbus0 (root)

SEE ALSO
     config(8)

AUTHORS
     Mats O Jansson <mojATstacken.se>

BUGS
     The add command is rather restricted, and might be expanded in the fu-
     ture.

OpenBSD 3.6                    December 13, 1998                             3