man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2014



devmap_default_access - default driver memory access function


#include <sys/ddi.h> 
#include <sys/sunddi.h>

int devmap_default_access(devmap_cookie_t dhp, void *pvtp, 
     offset_t off, size_t len, uint_t type, uint_t rw);

Interface Level

Solaris DDI specific (Solaris DDI).



An opaque mapping handle that the system uses to describe the mapping.


Driver private mapping data.


User offset within the logical device memory at which the access begins.


Length (in bytes) of the memory being accessed.


Type of access operation.


Type of access.


devmap_default_access() is a function providing the semantics of devmap_access(9E). The drivers call devmap_default_access () to handle the mappings that do not support context switching. The drivers should call devmap_do_ctxmgt(9F) for the mappings that support context management.

devmap_default_access() can either be called from devmap_access(9E) or be used as the devmap_access(9E) entry point. The arguments dhp, pvtp, off, len, type, and rw are provided by the devmap_access(9E) entry point and must not be modified.

Return Values


Successful completion.


An error occurred.


devmap_default_access() must be called from the driver's devmap_access(9E) entry point.


Example 1 Using devmap_default_access in devmap_access.

The following shows an example of using devmap_default_access() in the devmap_access(9E) entry point.

. . .
#define OFF_DO_CTXMGT  0x40000000
#define OFF_NORMAL     0x40100000
#define CTXMGT_SIZE    0x100000
#define NORMAL_SIZE    0x100000

 * Driver devmap_contextmgt(9E) callback function.
static int
xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset,
    size_t length, uint_t type, uint_t rw)
     * see devmap_contextmgt(9E) for an example

 * Driver devmap_access(9E) entry point
static int
xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off,
    size_t len, uint_t type, uint_t rw)
    offset_t diff;
    int err;

     * check if off is within the range that supports
     * context management.
    if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) {
         * calculates the length for context switching
        if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE))
            return (-1);
         * perform context switching
        err = devmap_do_ctxmgt(dhp, pvtp, off, len, type,
            rw,  xx_context_mgt);
     * check if off is within the range that does normal
     * memory mapping.
    } else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) {
        if ((len + off) > (OFF_NORMAL + NORMAL_SIZE))
            return (-1);
        err = devmap_default_access(dhp, pvtp, off, len, type, rw);
    } else
        return (-1);

    return (err);

See also

devmap_access(9E), devmap_do_ctxmgt(9F), devmap_callback_ctl(9S)

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