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1.\" 2.\" Copyright (c) 2003 Robert N. M. Watson 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice(s), this list of conditions and the following disclaimer as 10.\" the first lines of this file unmodified other than the possible 11.\" addition of one or more copyright notices. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice(s), this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 20.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 26.\" DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd February 18, 2004 31.Dt DISK 9 32.Os 33.Sh NAME 34.Nm disk 35.Nd kernel disk storage API 36.Sh SYNOPSIS 37.In geom/geom_disk.h 38.Ft struct disk * 39.Fn disk_alloc void 40.Ft void 41.Fn disk_create "struct disk *disk" "int version" 42.Ft void 43.Fn disk_gone "struct disk *disk" 44.Ft void 45.Fn disk_destroy "struct disk *disk" 46.Sh DESCRIPTION 47The disk storage API permits kernel device drivers providing access to 48disk-like storage devices to advertise the device to other kernel 49components, including 50.Xr GEOM 4 51and 52.Xr devfs 5 . 53.Pp 54Each disk device is described by a 55.Vt "struct disk" 56structure, which contains a variety of parameters for the disk device, 57function pointers for various methods that may be performed on the device, 58as well as private data storage for the device driver. 59In addition, some fields are reserved for use by GEOM in managing access 60to the device and its statistics. 61.Pp 62GEOM has the ownership of 63.Vt "struct disk" , 64and drivers must allocate storage for it with the 65.Fn disk_alloc 66function, 67fill in the fields and call 68.Fn disk_create 69when the device is ready to service requests. 70.Fn disk_gone 71orphans all of the providers associated with the drive, setting an error 72condition of ENXIO in each one. 73In addition, it prevents a re-taste on last close for writing if an error 74condition has been set in the provider. 75After calling 76.Fn disk_destroy , 77the device driver is not allowed to access the contents of 78.Vt "struct disk" 79anymore. 80.Pp 81The 82.Fn disk_create 83function 84takes a second parameter, 85.Fa version , 86which must always be passed 87.Dv DISK_VERSION . 88If GEOM detects that the driver is compiled against an unsupported version, 89it will ignore the device and print a warning on the console. 90.Ss Descriptive Fields 91The following fields identify the disk device described by the structure 92instance, and must be filled in prior to submitting the structure to 93.Fn disk_create 94and may not be subsequently changed: 95.Bl -tag -width indent 96.It Vt u_int Va d_flags 97Optional flags indicating to the storage framework what optional features 98or descriptions the storage device driver supports. 99Currently supported flags are 100.Dv DISKFLAG_NEEDSGIANT 101(maintained by device driver), 102.Dv DISKFLAG_OPEN 103(maintained by storage framework), 104.Dv DISKFLAG_CANDELETE 105(maintained by device driver), 106and 107.Dv DISKFLAG_CANFLUSHCACHE 108(maintained by device driver). 109.It Vt "const char *" Va d_name 110Holds the name of the storage device class, e.g., 111.Dq Li ahd . 112This value typically uniquely identifies a particular driver device, 113and must not conflict with devices serviced by other device drivers. 114.It Vt u_int Va d_unit 115Holds the instance of the storage device class, e.g., 116.Dq Li 4 . 117This namespace is managed by the device driver, and assignment of unit 118numbers might be a property of probe order, or in some cases topology. 119Together, the 120.Va d_name 121and 122.Va d_unit 123values will uniquely identify a disk storage device. 124.El 125.Ss Disk Device Methods 126The following fields identify various disk device methods, if implemented: 127.Bl -tag -width indent 128.It Vt "disk_open_t *" Va d_open 129Optional: invoked when the disk device is opened. 130If no method is provided, open will always succeed. 131.It Vt "disk_close_t *" Va d_close 132Optional: invoked when the disk device is closed. 133Although an error code may be returned, the call should always terminate 134any state setup by the corresponding open method call. 135.It Vt "disk_strategy_t *" Va d_strategy 136Mandatory: invoked when a new 137.Vt "struct bio" 138is to be initiated on the disk device. 139.It Vt "disk_ioctl_t *" Va d_ioctl 140Optional: invoked when an I/O control operation is initiated on the disk device. 141Please note that for security reasons these operations should not 142be able to affect other devices than the one on which they are performed. 143.It Vt "dumper_t *" Va d_dump 144Optional: if configured with 145.Xr dumpon 8 , 146this function is invoked from a very restricted system state after a 147kernel panic to record a copy of the system RAM to the disk. 148.It Vt "disk_getattr_t *" Va d_getattr 149Optional: if this method is provided, it gives the disk driver the 150opportunity to override the default GEOM response to BIO_GETATTR requests. 151This function should return -1 if the attribute is not handled, 0 if the 152attribute is handled, or an errno to be passed to g_io_deliver(). 153.It Vt "disk_gone_t *" Va d_gone 154Optional: if this method is provided, it will be called after disk_gone() 155is called, once GEOM has finished its cleanup process. 156Once this callback is called, it is safe for the disk driver to free all of 157its resources, as it will not be receiving further calls from GEOM. 158.El 159.Ss Mandatory Media Properties 160The following fields identify the size and granularity of the disk device. 161These fields must stay stable from return of the drivers open method until 162the close method is called, but it is perfectly legal to modify them in 163the open method before returning. 164.Bl -tag -width indent 165.It Vt u_int Va d_sectorsize 166The sector size of the disk device in bytes. 167.It Vt off_t Va d_mediasize 168The size of the disk device in bytes. 169.It Vt u_int Va d_maxsize 170The maximum supported size in bytes of an I/O request. 171Requests larger than this size will be chopped up by GEOM. 172.El 173.Ss Optional Media Properties 174These optional fields can provide extra information about the disk 175device. 176Do not initialize these fields if the field/concept does not apply. 177These fields must stay stable from return of the drivers open method until 178the close method is called, but it is perfectly legal to modify them in 179the open method before returning. 180.Bl -tag -width indent 181.It Vt u_int Va d_fwsectors , Vt u_int Va d_fwheads 182The number of sectors and heads advertised on the disk device by the 183firmware or BIOS. 184These values are almost universally bogus, but on some architectures 185necessary for the correct calculation of disk partitioning. 186.It Vt u_int Va d_stripeoffset , Vt u_int Va d_stripesize 187These two fields can be used to describe the width and location of 188natural performance boundaries for most disk technologies. 189Please see 190.Pa src/sys/geom/notes 191for details. 192.It Vt char Va d_ident[DISK_IDENT_SIZE] 193This field can and should be used to store disk's serial number if the 194d_getattr method described above isn't implemented, or if it does not 195support the GEOM::ident attribute. 196.It Vt char Va d_descr[DISK_IDENT_SIZE] 197This field can be used to store the disk vendor and product description. 198.It Vt uint16_t Va d_hba_vendor 199This field can be used to store the PCI vendor ID for the HBA connected to 200the disk. 201.It Vt uint16_t Va d_hba_device 202This field can be used to store the PCI device ID for the HBA connected to 203the disk. 204.It Vt uint16_t Va d_hba_subvendor 205This field can be used to store the PCI subvendor ID for the HBA connected to 206the disk. 207.It Vt uint16_t Va d_hba_subdevice 208This field can be used to store the PCI subdevice ID for the HBA connected to 209the disk. 210.El 211.Ss Driver Private Data 212This field may be used by the device driver to store a pointer to 213private data to implement the disk service. 214.Bl -tag -width indent 215.It Vt "void *" Va d_drv1 216Private data pointer. 217Typically used to store a pointer to the drivers 218.Vt softc 219structure for this disk device. 220.El 221.Sh SEE ALSO 222.Xr GEOM 4 , 223.Xr devfs 5 224.Sh AUTHORS 225This manual page was written by 226.An Robert Watson .