iovec(D4DK) —

NAME

iovec − data storage structure for I/O using uio(D4DK)

SYNOPSIS

#include <sys/types.h>
#include <sys/uio.h>

DESCRIPTION

An iovec structure describes a data storage area for transfer in a uio structure. Conceptually, it may be thought of as a base address and length specification.

STRUCTURE MEMBERS

caddr_t	iov_base;	/∗ base address of the data storage area ∗/
int	iov_len;	/∗ size of the data storage area in bytes ∗/

The driver may only set iovec structure members to initialize them for a data transfer for which the driver created the iovec structure. The driver must not otherwise change iovec structure members. However, drivers may read them. The iovec structure members available to the driver are:

iov_base contains the address for a range of memory to or from which data are transferred.

iov_len contains the number of bytes of data to be transferred to or from the range of memory starting at iov_base.

NOTES

A separate interface does not currently exist for allocating iovec(D4DK) structures when the driver needs to create them itself. Therefore, the driver may either use kmem_zalloc(D3DK) to allocate them, or allocate them statically.