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

illumos DDI specific (illumos 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 illumos 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);
        ....
}