man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2014



uiomove - copy kernel data using uio structure


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

int uiomove(caddr_t address, size_t nbytes, enum uio_rw rwflag, 
     uio_t *uio_p);

Interface Level

Architecture independent level 1 (DDI/DKI).



Source/destination kernel address of the copy.


Number of bytes to copy.


Flag indicating read or write operation. Possible values are UIO_READ and UIO_WRITE.


Pointer to the uio structure for the copy.


The uiomove() function copies nbytes of data to or from the space defined by the uio structure (described in uio(9S) ) and the driver.

The uio_segflg member of the uio(9S) structure determines the type of space to or from which the transfer is being made. If it is set to UIO_SYSSPACE, the data transfer is between addresses in the kernel. If it is set to UIO_USERSPACE, the transfer is between a user program and kernel space.

rwflag indicates the direction of the transfer. If UIO_READ is set, the data will be transferred from address to the buffer(s) described by uio_p. If UIO_WRITE is set, the data will be transferred from the buffer(s) described by uio_p to address.

In addition to moving the data, uiomove() adds the number of bytes moved to the iov_base member of the iovec(9S) structure, decreases the iov_len member, increases the uio_offset member of the uio(9S) structure, and decreases the uio_resid member.

This function automatically handles page faults. nbytes does not have to be word-aligned.

Return Values

The uiomove() function returns 0 upon success or EFAULT on failure.


User context only, if uio_segflg is set to UIO_USERSPACE. User, interrupt, or kernel context, if uio_segflg is set to UIO_SYSSPACE.

See also

ureadc(9F), uwritec(9F), iovec(9S), uio(9S)

Writing Device Drivers for Oracle Solaris 11.2


If uio_segflg is set to UIO_SYSSPACE and address is selected from user space, the system may panic.