aread - asynchronous read from a device
aread(dev_t dev, struct aio_req *aio_reqp, cred_t *cred_p);
illumos DDI specific (illumos DDI). This entry point is optional.
Drivers that do not support an aread() entry point should use
Pointer to the aio_req(9S)
describes where the data is to be stored.
Pointer to the credential structure.
The driver's aread() routine is called to perform an asynchronous read.
getminor(9F) can be used to access the minor number component of the
dev argument. aread() may use the credential structure pointed
to by cred_p to check for superuser access by calling
drv_priv(9F). The aread() routine may also examine the
uio(9S) structure through the aio_req structure pointer,
aio_reqp. aread() must call aphysio(9F) with the
aio_req pointer and a pointer to the driver's strategy(9E)
No fields of the uio(9S) structure pointed to by
aio_req, other than uio_offset or uio_loffset, may be
modified for non-seekable devices.
The aread() routine should return 0 for success, or the
appropriate error number.
This function is called from user context only.
Example 1 The following is an example of an aread() routine:
xxaread(dev_t dev, struct aio_req *aio, cred_t *cred_p)
struct xxstate *xsp;
instance = getminor(dev);
xsp = ddi_get_soft_state(statep, instance);
/*Verify soft state structure has been allocated */
if (xsp == NULL)
return (aphysio(xxstrategy, anocancel,
dev, B_READ, xxminphys, aio));
read(2), aioread(3C), awrite(9E), read(9E),
strategy(9E), write(9E), anocancel(9F),
aphysio(9F), ddi_get_soft_state(9F), drv_priv(9F),
getminor(9F), minphys(9F), nodev(9F), aio_req(9S),
Writing Device Drivers
There is no way other than calling aphysio(9F) to accomplish an