man pages section 9: DDI and DKI Kernel Functions

ddi_model_convert_from(9F)

Name

ddi_model_convert_from– determine data model type mismatch

Synopsis

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

 uint_tddi_model_convert_from(uint_t model);

Interface Level

Solaris DDI specific (Solaris DDI).

Parameters

model: The data model type of the current thread.

Description

ddi_model_convert_from() is used to determine if the current thread uses a different C Language Type Model than the device driver. The 64-bit version of Solaris will require a 64-bit kernel to support both 64-bit and 32-bit user mode programs. The difference between a 32-bit program and a 64-bit program is in its C Language Type Model: a 32-bit program is ILP32 (integer, longs, and pointers are 32-bit) and a 64-bit program is LP64 (longs and pointers are 64-bit). There are a number of driver entry points such as ioctl(9E) and mmap(9E) where it is necessary to identify the C Language Type Model of the user-mode originator of an kernel event. For example any data which flows between programs and the device driver or vice versa need to be identical in format. A 64-bit device driver may need to modify the format of the data before sending it to a 32-bit application. ddi_model_convert_from() is used to determine if data that is passed between the device driver and the application requires reformatting to any non-native data model.

Return Values

DDI_MODEL_ILP32: A conversion to/from ILP32 is necessary.
DDI_MODEL_NONE: No conversion is necessary. Current thread and driver use the same data model.

Context

ddi_model_convert_from() can be called from any context.

Examples

Example 1 : Using `ddi_model_convert_from()` in the `ioctl()` entry point to support both 32-bit and 64-bit applications.

The following is an example how to use ddi_model_convert_from() in the ioctl() entry point to support both 32-bit and 64-bit applications.

struct passargs32 {
        int len;
        caddr32_t addr;
};
 
struct passargs {
        int len;
        caddr_t addr;
};
xxioctl(dev_t dev, int cmd, intptr_t arg, int mode,
    cred_t *credp, int *rvalp) {
        struct passargs pa;
 
        switch (ddi_model_convert_from(mode & FMODELS)) {
            case DDI_MODEL_ILP32:
            {
                struct passargs32 pa32;

                ddi_copyin(arg, &pa32, sizeof (struct passargs32), mode);
                pa.len = pa32.len;
                pa.address = pa32.address;
                break;
            }
            case DDI_MODEL_NONE:
                ddi_copyin(arg, &pa, sizeof (struct passargs), mode);
                break;
        }

        do_ioctl(&pa);
        . . . .
}