BIO(4) Device Drivers Manual BIO(4)

bio — block I/O ioctl tunnel pseudo-device

pseudo-device bio [count]

The bio driver provides userland applications ioctl(2) access to devices otherwise not found as /dev nodes. The /dev/bio device node operates by delegating ioctl calls to a requested device driver. Only drivers which have registered with the bio device can be accessed via this interface.

If count is given in the specification, and is greater than 0, a maximum of one bio device is created.

The following device drivers register with bio for volume management:

ami(4)
American Megatrends Inc. MegaRAID PATA/SATA/SCSI RAID controller
arc(4)
Areca Technology Corporation SAS/SATA RAID controller
cac(4)
Compaq Smart Array 2/3/4 SCSI RAID controller
ciss(4)
Compaq Smart Array SAS/SATA/SCSI RAID controller
gdt(4)
ICP-Vortex and Intel GDT SATA/SCSI RAID controller
ips(4)
IBM SATA/SCSI ServeRAID controller
mfi(4)
LSI Logic & Dell MegaRAID SAS RAID controller
mfii(4)
LSI Logic MegaRAID SAS Fusion RAID controller
mpi(4)
LSI Logic Fusion-MPT Message Passing Interface
mpii(4)
LSI Logic Fusion-MPT Message Passing Interface II
nvme(4)
NVMe storage controllers
softraid(4)
Software RAID

The following device drivers register with bio to provide enclosure management:

safte(4)
SCSI Accessed Fault-Tolerant Enclosure
ses(4)
SCSI Enclosure Services

The following ioctl calls apply to the bio device:

struct bio_locate *
Locate a named device and give back a cookie to the application for subsequent ioctl calls. The cookie is used to tunnel further ioctls to the right device.
struct bioc_inq *
Retrieve number of volumes and physical disks for a specific device.
struct bioc_disk *
Retrieve detailed information for the specified physical disk. Information returned can include status, size, channel, target, lun, vendor name, serial number and processor device (ses or safte).
struct bioc_vol *
Retrieve detailed information for the specified volume. Information returned can include status, size, RAID level, number of disks, device name association (sd?) and vendor name.
struct bioc_alarm *
Control the alarm beeper on the device. Supported states are: disable alarm, enable alarm, silence alarm, status and test alarm.

Note: These options might not be supported on all hardware.

Blink an LED of the specified physical disk. Supported blink states are: blink LED, unblink LED and blink alarm LED.

Note: This option is only supported if the disk is governed by ses(4) or safte(4) and the hardware supports hardware blinking.

struct bioc_setstate *
Alter the state of specified physical disk. Supported states are: create hot-spare, online disk and offline disk.

The following ioctl calls apply to the bio device only when talking to a softraid(4) device:

struct bioc_createraid *
Create a new volume or assemble an existing volume. The volume will be attached as a system disk, if this capability is supported by the volume discipline.
struct bioc_deleteraid *
Remove system disk (if present) and disassemble the softraid(4) volume.
struct bioc_discipline *
Dispatch a discipline specific ioctl.
struct bioc_installboot *
Install a boot loader.

/dev/bio
ioctl tunnel device

ioctl(2), softraid(4), bioctl(8)

The bio driver first appeared in OpenBSD 3.2.

The bio driver was written by Niklas Hallqvist <niklas@openbsd.org>. The API was written by Marco Peereboom <marco@openbsd.org>.

OpenBSD 7.8 July 13, 2024 BIO(4)