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author | n_hibma <n_hibma@FreeBSD.org> | 1999-06-17 19:22:12 +0000 |
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committer | n_hibma <n_hibma@FreeBSD.org> | 1999-06-17 19:22:12 +0000 |
commit | 015d2f3ea84c1f4812ba70e7e5c7de5637c1c303 (patch) | |
tree | 986205ff158505cb086510228a04e70c6000b558 /share/man/man9/DEVICE_PROBE.9 | |
parent | 6491ecd71a0b7e46e7a85894f18dfee835d15e3c (diff) | |
download | FreeBSD-src-015d2f3ea84c1f4812ba70e7e5c7de5637c1c303.zip FreeBSD-src-015d2f3ea84c1f4812ba70e7e5c7de5637c1c303.tar.gz |
Update the comments on values than can be returned by DEVICE_PROBE.
DEVICE_PROBE can return priorities.
Reviewed by: Doug Rabson <dfr@nlsystems.com>
Diffstat (limited to 'share/man/man9/DEVICE_PROBE.9')
-rw-r--r-- | share/man/man9/DEVICE_PROBE.9 | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/share/man/man9/DEVICE_PROBE.9 b/share/man/man9/DEVICE_PROBE.9 index 412c8a5..6c853bf 100644 --- a/share/man/man9/DEVICE_PROBE.9 +++ b/share/man/man9/DEVICE_PROBE.9 @@ -26,7 +26,7 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $Id$ +.\" $Id: DEVICE_PROBE.9,v 1.1 1998/09/03 21:52:04 dfr Exp $ .\" .Dd June 16, 1998 .Os @@ -42,18 +42,36 @@ .Fn DEVICE_PROBE "device_t dev" .Sh DESCRIPTION .Pp -This device method should probe to see if the device is present. If -the device exists, the probe should return 0, otherwise ENXIO should -be returned. If some other error happens during the probe (such as a -memory allocation failure), an appropriate error code should be returned. +This device method should probe to see if the device is present. +It should return 0 if the device exists, ENXIO if it cannot be +found. If some other error happens during the probe (such as a memory +allocation failure), an appropriate error code should be returned. For +cases where more than one driver matches a device, a priority value can +be returned. In this case, success codes are values less than or equal +to zero with the highest value representing the best match. Failure +codes are represented by positive values and the regular unix error +codes should be used for the purpose. .Pp -Devices which implement busses should use this method to probe for the -existence of devices attached to the bus and add them as children. If -this is combined with the use of +If a driver returns a success code which is less than zero, it must +not assume that it will be the same driver which is attached to the +device. In particular, it must not assume that any values stored in +the softc structure will be available for its attach method and any +resources allocated during probe must be released and re-allocated +if the attach method is called. If a success code of zero is +returned, the driver can assume that it will be the one attached. +.Pp +Devices which implement busses should use this method to probe for +the existence of devices attached to the bus and add them as +children. If this is combined with the use of .Xr bus_generic_attach 9 the child devices will be automatically probed and attached. .Sh RETURN VALUES -Zero is returned on success, otherwise an error is returned. +A value equal to or less than zero indicates success, greater than +zero indicates an error (errno). For values equal to or less than +zero: zero indicates highest priority, no further probing is done; +for a value less then zero, the lower the value the lower the +priority, e.g. -100 indicates a lower priority than -50. + .Sh SEE ALSO .Xr device 9 , .Xr DEVICE_ATTACH 9 |