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ddi_model_convert_from - determine data model type mismatch

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

 uint_tddi_model_convert_from(uint_t model);

illumos DDI specific (illumos DDI). model 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. DDI_MODEL_ILP32 DDI_MODEL_NONE ddi_model_convert_from() can be called from any context. 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);
 .\|.\|.\|.
}

ioctl (9E), mmap (9E), ddi_mmap_get_model (9F)

Writing Device Drivers