device.hints(5)
NAME
device.hints - device resource hints
DESCRIPTION
- The device.hints file is read in by the boot loader(8) when
- the system is
about to start, and its contents are passed to the kernel. - It contains
various variables to control the boot behavior of the ker - nel. These
variables are typically ``device hints''. - The file contains one variable per line. Lines starting
- with the `#'
character are comments and are ignored by the boot loader. - After the file is read by the boot loader, you may examine
- the variables
with the show command, and may add a new variable, modify an - existing
one, or delete a variable with the set and unset commands of - the boot
loader (see loader(8)). - After the system has started, you can dump these variables
- with the
kenv(1) command.
DEVICE HINTS
- Device hint variables are used by device drivers to set up
- the device.
They are most often used by ISA device drivers to specify - where the
driver will probe for the relevant devices, and what re - sources it will
attempt to use. - A device hint line looks like:
hint.driver.unit.keyword="value"- where driver is the name of a device driver, unit is the
- unit number, and
keyword is the keyword of the hint. The keyword may be:
at specifies a bus to which the device is- attached.
port specifies the start address of I/O ports - to be used
by the device.
- portsize specifies the number of ports used by
- the device.
irq is the interrupt line number to be used.
drq is the DMA channel number.
maddr specifies the physical memory address - used by the
device.
- msize specifies the physical memory size used
- by the
device.
- flags sets various flag bits for the device.
disabled can be set to "1" to disable the device. - A device driver may require one or more hint lines with
- these keywords,
and may accept other keywords not listed here. Consult in - dividual device
drivers' manual pages for available keywords and their pos - sible values.
FILES
- /boot/device.hints Device re
- source hints
- file.
- /sys/ARCH/conf/GENERIC.hints Sample re
- source hints for
- the GENERIC
- kernel.
- /sys/ARCH/conf/NOTES Notes on the
- kernel con
- figuration
- file and
device re - source hints.
EXAMPLES
- The following example sets up resources for the sio(4) driv
- er on the ISA
bus:
hint.sio.0.at="isa"
hint.sio.0.port="0x3F8"
hint.sio.0.flags="0x10"
hint.sio.0.irq="4"- The following example disables the ACPI driver:
hint.acpi.0.disabled="1"
SEE ALSO
kenv(1), loader.conf(5), loader(8)
HISTORY
- The device.hints file first appeared in FreeBSD 5.0.
- BSD October 7, 2001