devmap_dup(9E)

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

Mapping handle of the mapping being duplicated.

new_handle

Mapping handle of the mapping that was duplicated.

devprivate

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 13-4 shows a devmap_dup(9E) routine.

Example 13-4 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);
}