1ldi_open_by_dev(9F) Kernel Functions for Drivers ldi_open_by_dev(9F)
2
6 ldi_open_by_dev, ldi_open_by_name, ldi_open_by_devid, ldi_close - open
7 and close devices
8
10 #include <sys/sunldi.h>
11 int ldi_open_by_dev(dev_t *devp, int otyp, int flag, cred_t *cr,
13 ldi_handle_t *lhp, ldi_ident_t li);
14 int ldi_open_by_name(char *pathname, int flag, cred_t *cr,
17 ldi_handle_t *lhp, ldi_ident_t li);
18 int ldi_open_by_devid(ddi_devid_t devid, char *minor_name, int flag,
21 cred_t *cr, ldi_handle_t *lhp, ldi_ident_t li);
22 int ldi_close(ldi_handle_t lh, int flag, cred_ t *cr);
25
28 lh Layered handle
29 lhp Pointer to a layered handle that is returned upon a suc‐
32 cessful open.
33 li LDI identifier.
36 cr Pointer to the credential structure used to open a
39 device.
40 devp Pointer to a device number.
43 pathname Pathname to a device.
46 devid Device ID.
49 minor_name Minor device node name.
52 otyp Flag passed to the driver indicating which interface is
55 open. Valid settings are:
56 OTYP_BLK Open the device block interface.
58 OTYP_CHR Open the device character interface.
61 Only one OTYP flag can be specified. To open streams
63 devices, specify OTYP_CHR.
64 flag Bit field that instructs the driver on how to open the
67 device. Valid settings are:
68 FEXCL Open the device with exclusive access; fail
70 all other attempts to open the device.
71 FNDELAY Open the device and return immediately. Do
74 not block the open even if something is wrong.
75 FREAD Open the device with read-only permission. (If
78 ORed with FWRITE, allow both read and write
79 access).
80 FWRITE Open a device with write-only permission (if
83 ORed with FREAD, then allow both read and
84 write access).
85 FNOCTTY Open the device. If the device is a tty, do
88 not attempt to open it as a session-control‐
89 ling tty.
90
94 The ldi_open_by_dev(), ldi_open_by_name() and ldi_open_by_devid() func‐
95 tions allow a caller to open a block, character, or streams device.
96 Upon a successful open, a layered handle to the device is returned via
97 the layered handle pointed to by lhp. The ldi identifier passed to
98 these functions is previously allocated with ldi_ident_from_stream(9F),
99 ldi_ident_from_dev(9F), and ldi_ident_from_dip(9F).
100 The ldi_open_by_dev() function opens a device specified by the dev_t
103 pointed to by devp. Upon successful open, the caller should check the
104 value of the dev_t to see if it has changed. (Cloning devices will
105 change this value during opens.) When opening a streams device, otyp
106 must be OTYP_CHR.
107 The ldi_open_by_devid() function opens a device by devid. The caller
110 must specify the minor node name to open.
111 The ldi_open_by_name() function opens a device by pathname. Pathname is
114 a null terminated string in the kernel address space. Pathname must be
115 an absolute path, meaning that it must begin with '/'. The format of
116 the pathname supplied to this function is either a /devices path or any
117 other filesystem path to a device node. Opens utilizing /devices paths
118 are supported before root is mounted. Opens utilizing other filesystem
119 paths to device nodes are supported only if root is already mounted.
120 The ldi_close() function closes a layered handle that was obtained with
123 either ldi_open_by_dev(), ldi_open_by_name(), or ldi_open_by_devid().
124 After ldi_close() returns the layered handle, the lh that was previ‐
125 ously passed in is no longer valid.
126
128 The ldi_close() function returns 0 for success. EINVAL is returned for
129 invalid input parameters. Otherwise, any other error number may be
130 returned by the device.
131 The ldi_open_by_dev() and ldi_open_by_devid() functions return 0 upon
134 success. If a failure occurs before the device is open, possible return
135 values are shown below. Otherwise any other error number may be
136 returned by the device.
137 EINVAL Invalid input parameters.
139 ENODEV Requested device does not exist.
142 ENXIO Unsupported device operation or access mode.
145 The ldi_open_by_name() function returns 0 upon success. If a failure
149 occurs before the device is open, possible return values are shown
150 below. Otherwise any other error number may be returned by the device.
151 EINVAL Invalid input parameters.
153 ENODEV Requested device path does not exist.
156 EACCES Search permission is denied on a component of the path pre‐
159 fix, or the file exists and the permissions specified by cr
160 are denied.
161 ENXIO Unsupported device operation or access mode.
164
167 These functions may be called from user or kernel context.
168 These functions should not be called from a device's attach, detach, or
171 power entry point. This could result in a system crash or deadlock.
172
174 scsi_vhci(7D), ldi_ident_from_dev(9F), ldi_ident_from_dip(9F),
175 ldi_ident_from_stream(9F)
176
178 Use only OTYP_CHR or OTYP_BLK options when you use the
179 ldi_open_by_dev() and ldi_open_by_devid() functions to open a device.
180 Other flags, including OTYP_LYR, have been deprecated and should not be
181 used with these interfaces.
182 The caller should be aware of cases when multiple paths to a single
185 device may exist. (This can occur for scsi disk devices if
186 scsi_vhci(7D)) is disabled or a disk is connected to multiple con‐
187 trollers not supported by scsi_vhci(7D).
188 In these cases, ldi_open_by_devid() returns a device handle that corre‐
191 sponds to a particular path to a target device. This path may not be
192 the same across multiple calls to ldi_open_by_devid(). Device handles
193 associated with the same device but different access paths should have
194 different filesystem device paths and dev_t values.
195 In the cases where multiple paths to a device exist and access to the
198 device has not been virtualized via MPXIO (as with scsi disk devices
199 not accessed via scsi_vhci(7D)), the LDI does not provide any path
200 fail-over capabilities. If the caller wishes to do their own path man‐
201 agement and failover they should open all available paths to a device
202 via ldi_open_by_name().
203SunOS 5.11 9 Aug 2004 ldi_open_by_dev(9F)