tail head cat sleep
QR code linking to this page

Manual Pages  — NDISCVT


ndiscvt – convert Windows[rg] NDIS drivers for use with FreeBSD



ndiscvt [-O] [-i inffile] -s sysfile [-n devname] [-o outfile]
ndiscvt [-f firmfile]


The ndiscvt utility transforms a Windows[rg] NDIS driver into a data file which is used to build an ndis(4) compatibility driver module. Windows[rg] drivers consist of two main parts: a .SYS file, which contains the actual driver executable code, and an .INF file, which provides the Windows[rg] installer with device identifier information and a list of driver-specific registry keys. The ndiscvt utility can convert these files into a header file that is compiled into if_ndis.c to create an object code module that can be linked into the FreeBSD kernel.

The .INF file is typically required since only it contains device identification data such as PCI vendor and device IDs or PCMCIA identifier strings. The .INF file may be optionally omitted however, in which case the ndiscvt utility will only perform the conversion of the .SYS file. This is useful for debugging purposes only.


The options are as follows:
-i inffile
  Open and parse the specified .INF file when performing conversion. The ndiscvt utility will parse this file and emit a device identification structure and registry key configuration structures which will be used by the ndis(4) driver and ndisapi(9) kernel subsystem. If this is omitted, ndiscvt will emit a dummy configuration structure only.
-s sysfile
  Open and parse the specified .SYS file. This file must contain a Windows[rg] driver image. The ndiscvt utility will perform some manipulation of the sections within the executable file to make runtime linking within the kernel a little easier and then convert the image into a data array.
-n devname
  Specify an alternate name for the network device/interface which will be created when the driver is instantiated. If you need to load more than one NDIS driver into your system (i.e., if you have two different network cards in your system which require NDIS driver support), each module you create must have a unique name. Device can not be larger than IFNAMSIZ. If no name is specified, the driver will use the default a default name ("ndis").
-o outfile
  Specify the output file in which to place the resulting data. This can be any file pathname. If outfile is a single dash ('-'), the data will be written to the standard output. The if_ndis.c module expects to find the driver data in a file called ndis_driver_data.h, so it is recommended that this name be used.
  Generate both an ndis_driver_data.h file and an ndis_driver.data.o file. The latter file will contain a copy of the Windows[rg] .SYS driver image encoded as a FreeBSD ELF object file (created with objcopy(1)). Turning the Windows[rg] driver image directly into an object code file saves disk space and compilation time.
-f firmfile
  A few NDIS drivers come with additional files that the core driver module will load during initialization time. Typically, these files contain firmware which the driver will transfer to the device in order to make it fully operational. In Windows[rg], these files are usually just copied into one of the system directories along with the driver itself.

In FreeBSD there are two mechanism for loading these files. If the driver is built as a loadable kernel module which is loaded after the kernel has finished booting (and after the root file system has been mounted), the extra files can simply be copied to the /compat/ndis directory, and they will be loaded into the kernel on demand when the driver needs them.

If however the driver is required to bootstrap the system (i.e., if the NDIS-based network interface is to be used for diskless/PXE booting), the files need to be pre-loaded by the bootstrap loader in order to be accessible, since the driver will need them before the root file system has been mounted. However, the bootstrap loader is only able to load files that are shared FreeBSD binary objects.

The -f flag can be used to convert an arbitrary file firmfile into shared object format (the actual conversion is done using the objcopy(1) and ld(1) commands). The resulting files can then be copied to the /boot/kernel directory, and can be pre-loaded directly from the boot loader prompt, or automatically by editing the loader.conf(5) file. If desired, the files can also be loaded into memory at runtime using the kldload(8) command.

When an NDIS driver tries to open an external file, the ndisapi(9) code will first search for a loaded kernel module that matches the name specified in the open request, and if that fails, it will then try to open the file from the /compat/ndis directory as well. Note that during kernel bootstrap, the ability to open files from /compat/ndis is disabled: only the module search will be performed.

When using the -f flag, ndiscvt will generate both a relocatable object file (with a .o extension) and a shared object file (with a .ko extension). The shared object is the one that should be placed in the /boot/kernel directory. The relocatable object file is useful if the user wishes to create a completely static kernel image: the object file can be linked into the kernel directly along with the driver itself. Some editing of the kernel configuration files will be necessary in order to have the extra object included in the build.


ld(1), objcopy(1), ndis(4), kldload(8)


The ndiscvt utility first appeared in FreeBSD 5.3 .


The ndiscvt utility was written by Bill Paul <Mt wpaul@windriver.com>. The lex(1) and yacc(1) INF file parser was written by Matthew Dodd <Mt mdodd@FreeBSD.org>.

NDISCVT (8) December 10, 2003

tail head cat sleep
QR code linking to this page

Please direct any comments about this manual page service to Ben Bullock. Privacy policy.

"I liken starting one's computing career with Unix, say as an undergraduate, to being born in East Africa. It is intolerably hot, your body is covered with lice and flies, you are malnourished and you suffer from numerous curable diseases. But, as far as young East Africans can tell, this is simply the natural condition and they live within it. By the time they find out differently, it is too late. They already think that the writing of shell scripts is a natural act."
— Ken Pier, Xerox PARC