disk(4) FreeBSD Kernel Interfaces Manual disk(4)
NAME
disk - common disk interfaces
SYNOPSIS
device cd
DESCRIPTION
Common block device IOCTLs
All the block devices in the system should support these disk ioctl(2)
commands defined here. Much of this information is also available via
the geom(2) attributes.
IOCTLS
The following ioctl(2) calls apply to disk drives, and are defined in the
<sys/disk.h> header file.
DIOCGSECTORSIZE (u_int) Get the sector or block size of the device in
bytes. The sector size is the smallest unit of data
which can be transferred from this device. This is
usually a power of 2 but it might not be (e.g. CDROM
audio). Operations to block devices such as lseek(2),
read(2), and write may only be performed at file
offsets that are integral multiple of this size.
DIOCGMEDIASIZE (off_t) Get the size of the entire device in bytes.
This should be a multiple of the sector size.
DIOCGFWSECTORS (u_int) Return the firmware's notion of number of
sectors per track. This value is mostly used for
compatibility with various ill designed disk label
formats. Use this value only when absolutely
required. Its interpretation and use is largely
obsolete.
DIOCGFWHEADS (u_int) Return the firmware's notion of number of
heads per cylinder. This value is mostly used for
compatibility with various ill designed disk label
formats. Use this value only when absolutely
required. Its interpretation and use is largely
obsolete.
DIOCGFLUSH Flush write cache of the device.
DIOCGDELETE (off_t[2]) Mark data on the device as unused. The
first element is the offset to start deleting. The
second element is the length to delete. Providers may
use this information to free storage or instruct
storage devices the contents can be discarded.
DIOCGIDENT (char[DISK_IDENT_SIZE]) Get the ident for this
provider. Ident is a unique and fixed identifier for
this provider. Ident's properties are as follow:
• preserved between reboots,
• preserved across a provider being
detached/attached,
• provider's name can change - ident can't,
• ident value should not be based on on-disk
metadata; in other words, copying whole data from
one disk to another should not yield the same
ident for the other disk,
• there can be more than one provider with the same
ident, but only if they point at exactly the same
physical storage, this is the case for
multipathing for example,
• GEOM classes that consume a single provider and
provide single provider, like geli(8), and
gbde(8), the identifier should be formed by
attaching that provider's class name to the ident
of the underlying provider,
• ident is an NUL-terminated ASCII string (is
printable),
• ident is optional and applications can't relay on
its presence.
DIOCGPROVIDERNAME (char[MAXPATHLEN]) Store the provider name for the
device in a buffer. The buffer must be at least
MAXPATHLEN bytes long.
DIOCGSTRIPESIZE (off_t) Get the size of the device's optimal access
block in bytes. This should be a multiple of the
sector size.
DIOCGSTRIPEOFFSET (off_t) Get the offset of the first device's optimal
access block in bytes. This should be a multiple of
the sector size.
DIOCGPHYSPATH (char[MAXPATHLEN]) Get a string defining the physical
path for a given provider. This has similar rules to
ident, but is intended to uniquely identify the
physical location of the device, not the current
occupant of that location. The buffer must be at
least MAXPATHLEN bytes long.
DIOCGATTR (struct diocgattr_arg)
struct diocgattr_arg {
char name[64];
int len;
union {
char str[DISK_IDENT_SIZE];
off_t off;
int i;
uint16_t u16;
} value;
};
Get a geom attribute from the provider. Format of the
returned data is specific to the attribute.
DIOCZONECMD (struct disk_zone_arg) Send disk zone commands.
DIOCSKERNELDUMP (struct diocskerneldump_arg) Enable/Disable the device
for kernel core dumps.
DIOCGKERNELDUMP (struct diocskerneldump_arg) Get current kernel
netdump configuration details for a given index.
/*
* Sentinel values for kda_index.
*
* If kda_index is KDA_REMOVE_ALL, all dump configurations are cleared.
*
* If kda_index is KDA_REMOVE_DEV, all dump configurations for the specified
* device are cleared.
*
* If kda_index is KDA_REMOVE, only the specified dump configuration for the
* given device is removed from the list of fallback dump configurations.
*
* If kda_index is KDA_APPEND, the dump configuration is added after all
* existing dump configurations.
*
* Otherwise, the new configuration is inserted into the fallback dump list at
* index 'kda_index'.
*/
#define KDA_REMOVE UINT8_MAX
#define KDA_REMOVE_ALL (UINT8_MAX - 1)
#define KDA_REMOVE_DEV (UINT8_MAX - 2)
#define KDA_APPEND (UINT8_MAX - 3)
struct diocskerneldump_arg {
uint8_t kda_index;
uint8_t kda_compression;
uint8_t kda_encryption;
uint8_t kda_key[KERNELDUMP_KEY_MAX_SIZE];
uint32_t kda_encryptedkeysize;
uint8_t *kda_encryptedkey;
char kda_iface[IFNAMSIZ];
union kd_ip kda_server;
union kd_ip kda_client;
union kd_ip kda_gateway;
uint8_t kda_af;
};
HISTORY
The manual page was written by M Warner Losh <imp@FreeBSD.org> from text
largely derived from <sys/disk.h>.
FreeBSD 13.1-RELEASE-p6 November 20, 2020 FreeBSD 13.1-RELEASE-p6
man2web Home...