devmap_dup()

int xxdevmap_dup(devmap_cookie_t handle, void *devprivate,
 	devmap_cookie_t new_handle, void **new_devprivate);

This entry point is called when a device mapping is duplicated, for example, by a user process calling fork(2). The driver is expected to generate new driver private data for the new mapping.

handle is the mapping handle of the mapping being duplicated.

new_handle is the mapping handle of the mapping that was duplicated.

devprivate is a pointer to the driver private data associated with the mapping being duplicated.

*new_devprivate should be set to point to the new driver private data for the new mapping.

Mappings created with devmap_dup(9E) will, by default, have their mapping translations invalidated. This will force a call to the devmap_access(9E) entry point the first time the mapping is accessed.

Example 12-5 shows a devmap_dup(9E) routine.

Example 12-5 devmap_dup(9E) Routine

static int
xxdevmap_dup(devmap_cookie_t handle, void *devprivate,
	devmap_cookie_t new_handle, void **new_devprivate)
{
 	struct xxctx *ctxp = devprivate;
 	struct xxstate *xsp = ctxp->xsp;
 	struct xxctx *newctx;
 	/* Create a new context for the duplicated mapping */
 	newctx = kmem_alloc(sizeof (struct xxctx), KM_SLEEP);
 	newctx->xsp = xsp;
 	newctx->handle = new_handle;
 	newctx->offset = ctxp->offset;
 	newctx->flags = ctxp->flags;
 	newctx->len = ctxp->len;
 	mutex_enter(&xsp->ctx_lock);
 	if (ctxp->flags & MAP_PRIVATE) {
	   	  newctx->context = kmem_alloc(XXCTX_SIZE, KM_SLEEP);
	   	  bcopy(ctxp->context, newctx->context, XXCTX_SIZE);
 	} else {
	    	  newctx->context = xsp->ctx_shared;
 	}
 	mutex_exit(&xsp->ctx_lock);
 	*new_devprivate = newctx;
 	return(0);
}