ddi_model_convert_from(9F)				   Kernel Functions for Drivers 				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);
	       ....
       }

SEE ALSO

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

       Writing Device Drivers

SunOS 5.10							    8 Feb 2001						ddi_model_convert_from(9F)