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.Dd Apr 29 2024
.Dt DEVICE 9
.Os Hyra
.Sh NAME
.Nm device - hyra device subsystem
.Sh SYNOPSIS
.In sys/device.h
.Sh DESCRIPTION
Devices registered with the kernel are represented by the device structure:

.Bd -literal
struct device {
    dev_t major, minor;
    size_t blocksize;
    int(*write)(struct device *dev, struct sio_txn *sio);
    int(*read)(struct device *dev, struct sio_txn *sio);
    int(*ioctl)(struct device *dev, uint32_t cmd, uintptr_t arg);
    ...
    TAILQ_ENTRY(device) link;
};
.Ed

Device instances are to be allocated with the
.Ft device_alloc()
function. These instances are registered with the kernel by the
.Ft device_create()
function.

The major number identifies the driver and the minor number identifies
the device itself. The major number must be allocated with the
.Ft device_alloc_major()
function.

If the device blocksize is greater than 1, this device is considered a block
device, otherwise if it is 1, it is considered a character device.

.Sh AUTHORS
.An Ian Moffett Aq Mt ian@osmora.org