SCO OpenServer

copyio(D3oddi)

copyio -- copy bytes between a physical and a virtual address

Synopsis

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

int copyio(paddr_t paddr, caddr_t caddr, int bytes, int mapping);

Description

The copyio function copies bytes between physical addresses and kernel virtual addresses, and between kernel addresses and user addresses. This routine has little purpose other than to call bcopy(D3oddi) for transfers between kernel addresses, copyin(D3oddi) for transfers from user space to the kernel, and copyout(D3oddi) for transfers from the kernel to user space.

Arguments

paddr

Pointer to a physical address to which, or from which, data is to be transferred.

caddr

Virtual address to which, or from which, data is to be transferred.

bytes

integer that specifies the number of bytes of data to transfer.

mapping

integer that designates the direction of the transfer. The following possible mapping values are defined in the <sys/user.h> header file. Use of any other value causes a system panic.

U_RKD: Kernel-to-kernel transfer from paddr to caddr using bcopy.
U_WKD: Kernel-to-kernel transfer from caddr to paddr using bcopy.
U_RUD: Kernel-to-user transfer from paddr to caddr using copyout.
U_WUD: User-to-kernel transfer from caddr to paddr using copyin.

Return values

If successful, this routine performs the specified data transfer. Otherwise, -1 is returned for any mapping setting if the requested number of bytes to transfer is 0 (zero). The following errors can also occur only when copyio is called with the U_RUD or U_WUD mappings:

The address in user space is invalid, causing a page fault to occur during a transfer to or from user space.
An address was specified that would have resulted in data being copied into priviliged address space such as the user block.

If U_RUD or U_WUD is set in mapping and -1 is returned, call seterror to return EFAULT to the calling process in user space.

Usage

Always include <sys/user.h> and select a correct mapping value. Otherwise, a panic occurs with the message ``bad mapping in copyio''.

Specify kernel addresses only for mapping set to U_RKD or U_WKD. If a user address is specified for these mappings, the system will panic.

When this function is called from the read(D2oddi) or write(D2oddi) entry point with the U_RUD or U_WUD mapping, the driver code must increase u.u_base and u.u_offset by the number of bytes transferred, and decrease u.u_count by the number of bytes transferred after the call completes:

   u.u_count -= cnt;
   u.u_offset += cnt;
   u.u_base += cnt;

The iomove(D3oddi) function is similar to copyio( ), but it sets the members of the user area and the driver does not have to.

If an error code is returned, call seterror(D3oddi) with argument EFAULT to return EFAULT to the user process calling your driver. Address values need not be word-aligned.

Context and synchronization

If mapping is U_RUD or U_WUD: User context.
If mapping is U_RKD or U_WKD: All contexts.

Hardware applicability

All

Version applicability

oddi: 1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp, 6, 6mp

SVR5 DDI compatibility

This function is not supported in DDI. This function can be replaced with calls to bcopy(D3) for transfers between kernel addresses, copyin(D3) for transfers from user space to the kernel, and copyout(D3) for transfers from the kernel to user space.

References

bcopy(D3oddi), copyin(D3oddi), copyout(D3oddi), cpass(D3oddi), fubyte(D3oddi), fuword(D3oddi), iomove(D3oddi), passc(D3oddi), seterror(D3oddi), subyte(D3oddi), suword(D3oddi)

``Data, copying'' in HDK Technical Reference