AREAD(9E)AREAD(9E)NAMEaread - asynchronous read from a device
SYNOPSIS
#include <sys/uio.h>
#include <sys/aio_req.h>
#include <sys/cred.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
intprefix
aread(dev_t dev, struct aio_req *aio_reqp, cred_t *cred_p);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI). This entry point is optional.
Drivers that do not support an aread() entry point should use nodev(9F)PARAMETERS
dev
Device number.
aio_reqp
Pointer to the aio_req(9S) structure that describes where
the data is to be stored.
cred_p
Pointer to the credential structure.
DESCRIPTION
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) routine.
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.
RETURN VALUES
The aread() routine should return 0 for success, or the appropriate
error number.
CONTEXT
This function is called from user context only.
EXAMPLES
Example 1 The following is an example of an aread() routine:
static int
xxaread(dev_t dev, struct aio_req *aio, cred_t *cred_p)
{
int instance;
struct xxstate *xsp;
instance = getminor(dev);
xsp = ddi_get_soft_state(statep, instance);
/*Verify soft state structure has been allocated */
if (xsp == NULL)
return (ENXIO);
return (aphysio(xxstrategy, anocancel,
dev, B_READ, xxminphys, aio));
}
SEE ALSOread(2), aioread(3C), awrite(9E), read(9E), strategy(9E), write(9E),
anocancel(9F), aphysio(9F), ddi_get_soft_state(9F), drv_priv(9F), get‐
minor(9F), minphys(9F), nodev(9F), aio_req(9S), cb_ops(9S), uio(9S)
Writing Device Drivers
BUGS
There is no way other than calling aphysio(9F) to accomplish an asyn‐
chronous read.
Mar 28, 1997 AREAD(9E)