hw inde dd.htm

What is this ``device driver stuff anyway? Here s a very short introduction to the concept.

<a name="nx_id_662"></a>
</p></li></ul><p>
<a name="BusSupprtSub"></a>
</p><p></p><hr><p align="center">
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/Digital_UNIX_Bookshelf.html"><img src="HW%20inde%20DD_files/BOOKSHELF.GIF" alt="[Return to Library]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/TOC.html"><img src="HW%20inde%20DD_files/TOC.GIF" alt="[Contents]" border="0"></a>
<a href="#HWIndepModelandDrvs"><img src="HW%20inde%20DD_files/REW.GIF" alt="[Previous Chapter]" border="0"></a>
<a href="#HardDepInter"><img src="HW%20inde%20DD_files/PREV.GIF" alt="[Previous Section]" border="0"></a>
<a href="#DevDrvSub"><img src="HW%20inde%20DD_files/NEXT.GIF" alt="[Next Section]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/drivertut22.html"><img src="HW%20inde%20DD_files/FF.GIF" alt="[Next Chapter]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/INDEX.html"><img src="HW%20inde%20DD_files/INDEX.GIF" alt="[Index]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/HELP.html"><img src="HW%20inde%20DD_files/HELP.GIF" alt="[Help]" border="0"></a>
</p><p></p><hr><p>
</p><h2>
15.3&nbsp;&nbsp;&nbsp;&nbsp;Bus Support Subsystem
</h2>
<p>
The bus support subsystem contains all of the bus adapter-specific code.
<a name="nx_id_663"></a>
Many buses provide interfaces that are publicly documented and,
therefore, allow vendors to more easily plug in hardware and 
software components.
However, the way one vendor implements the bus-specific code can be
different from another vendor.
For example, the implementation of the VMEbus on Digital Alpha systems is
different from Sun Microsystem's implementation of the VMEbus.
Isolating the bus-specific code and data structures into a bus support
subsystem makes it easier for independent software vendors to implement
different bus adapters.
<a name="nx_id_664"></a>
<a name="nx_id_665"></a>
</p><p>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/drivertut21.html#HardIndModel">Figure 15-1</a>
shows that the bus support subsystem communicates with: 
</p><ul>
<p></p><li>
The hardware-dependent subsystem
<p>
The bus support subsystem communicates with the
hardware-dependent subsystem by calling interfaces and referencing
data structures and global variables provided by the hardware-dependent
subsystem.
<a name="nx_id_666"></a>
</p><p></p></li><li>
The device driver subsystem
<p>
The bus support subsystem communicates with the
device driver subsystem during device autoconfiguration through the
driver's
<tt>probe</tt>,
<tt>slave</tt>,
and
<tt>attach</tt>
interfaces.
In addition, the bus support subsystem provides interfaces that allow
drivers to perform bus-specific tasks.
</p></li></ul><p>
<a name="nx_id_667"></a>
<a name="DevDrvSub"></a>
</p><p></p><hr><p align="center">
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/Digital_UNIX_Bookshelf.html"><img src="HW%20inde%20DD_files/BOOKSHELF.GIF" alt="[Return to Library]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/TOC.html"><img src="HW%20inde%20DD_files/TOC.GIF" alt="[Contents]" border="0"></a>
<a href="#HWIndepModelandDrvs"><img src="HW%20inde%20DD_files/REW.GIF" alt="[Previous Chapter]" border="0"></a>
<a href="#BusSupprtSub"><img src="HW%20inde%20DD_files/PREV.GIF" alt="[Previous Section]" border="0"></a>
<img src="HW%20inde%20DD_files/BLANK.GIF" border="0">
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/drivertut22.html"><img src="HW%20inde%20DD_files/FF.GIF" alt="[Next Chapter]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/INDEX.html"><img src="HW%20inde%20DD_files/INDEX.GIF" alt="[Index]" border="0"></a>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/HELP.html"><img src="HW%20inde%20DD_files/HELP.GIF" alt="[Help]" border="0"></a>
</p><p></p><hr><p>
</p><h2>
15.4&nbsp;&nbsp;&nbsp;&nbsp;Device Driver Subsystem
</h2>
<p>
The device driver subsystem contains all of the driver-specific code.
<a name="nx_id_668"></a>
This subsystem is supplied by Digital Equipment Corporation and
includes device drivers for hardware supported by Digital.
Third-party device driver writers would place their drivers in the
device driver subsystem.
</p><p>
<a href="http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/HTML/AA-PUBVD-TE_html/drivertut21.html#HardIndModel">Figure 15-1</a>
shows that the device driver subsystem communicates with: 
</p><ul>
<p></p><li>
The hardware-dependent subsystem
<p>
The device driver subsystem communicates with the
hardware-dependent subsystem by calling interfaces and referencing
data structures and global variables provided by the hardware-dependent
subsystem.
<a name="nx_id_669"></a>
</p><p></p></li><li>
The bus support subsystem
<p>
The device driver subsystem communicates with the bus support subsystem
during device autoconfiguration.
This is accomplished through the driver's
<tt>probe</tt>,
<tt>slave</tt>,
and
<tt>attach</tt>
interfaces.
In addition, device drivers can call bus-specific interfaces to perform
a variety of tasks.
For example, a TURBOchannel device driver calls the
<tt>tc_isolate_memerr</tt>
interface to log memory-related errors.
Other buses have their own specific interfaces that drivers use to
communicate with this subsystem.
</p><p>
Device drivers can also call generic interfaces such as
<tt>io_copyin</tt>
to copy data from bus address space to system memory.
The advantage to calling the generic interface as opposed to the
bus-specific interface is that the generic interface makes the driver
more portable across different bus architectures.
<a name="nx_id_670"></a>
</p><p></p></li><li>
The hardware-independent subsystem
<p>
The device driver subsystem communicates with the hardware-independent subsystem
through calls to interfaces and data structures provided by the
hardware-independent subsystem.
</p></li></ul><p>
<a name="nx_id_671"></a>
<!--Metrics Tag -->
 <!-- Updated April 22, 2003 --> 
<!-- SiteCatalyst code version: G.0. w/dev site filtering
Copyright 1997-2003 Omniture, Inc. More info available at
http://www.omniture.com --><script language="JavaScript"><!--
/* Specify the Report Suite ID(s) to track here */
var s_account="HPHQGlobal,hphqWWesg,hphqbcs,hphqtru64"
/* Dynamic Report Suite ID Selection Config */
var s_dynamicAccountSelection = true
var s_dynamicAccountList = "hphqwwtrash=dec.com,cpqcorp.net,hpqcorp.net"
/* You may give each page an identifying user friendly name in place of urls. */
var s_pageName="Tru64-" + document.title;
if ( location.pathname.indexOf('/docs' ) != -1 )         { s_pageName = "Tru64-docs-" + document.title; }

/* Regionally assigned variables. */
var s_server=""
var s_channel=""
var s_pageType=""
var s_prop1="Tru64 UNIX"
if ( location.pathname.indexOf('/docs' ) != -1 )         { s_prop1 = "Tru64 documentation"; }
var s_prop2 = "";

   if ( location.search.indexOf('?jumpid=' ) != -1 )
        {
        s_prop2=location.search.substring((location.search.indexOf('?jumpid=' )+8),(location.search.length));
        }
			else
		{ 
		if (location.search.toUpperCase().indexOf('?' ) != -1 )        {
		s_prop2=location.search.toUpperCase().substring((location.search.toUpperCase().indexOf('?' )+1),(location.search.length));
		}
		}
var s_prop6=""
var s_prop7="w1"
var s_prop8="en-us"
var s_prop9="enterprise"
var s_prop10="w1|en-us|enterprise"
var s_prop13="HPHQGlobal,hphqWWesg,hphqbcs,hphqtru64"


/************************ ADDITIONAL FEATURES ************************
     Plugins
*/
/************************** CONFIG SECTION **************************/
/* You may add or alter any code config here.                       */
var s_charSet=""
// Netscape 4.X on Unix uses EUC-JP instead of SHIFT-JIS
if ((navigator.appName.indexOf('Netscape')>=0)&&
    (parseInt(navigator.appVersion)<=4)&&
    (navigator.userAgent.toLowerCase().indexOf('win')<0)&&
    (navigator.userAgent.toLowerCase().indexOf('mac')<0)) {
	s_charSet="EUC-JP"
}
/* E-commerce Config */
var s_eVarCFG=""

/* Link Tracking Config */
var s_trackDownloadLinks=true
var s_trackExternalLinks=true
var s_trackInlineStats=true
var s_linkDownloadFileTypes="exe,zip,wav,mp3,mov,mpg,avi,doc,pdf,xls,cgi,dot,pot,ppt,wmv,cgi,asx,tar,rpm,gz,crypt,sh"
var s_linkInternalFilters="hp,compaq,javascript:"
var s_linkLeaveQueryString=true


/********* INSERT THE DOMAIN AND PATH TO YOUR CODE BELOW ************/
//--></script><script language="JavaScript" src="HW%20inde%20DD_files/s_code.js"></script><img src="HW%20inde%20DD_files/s58093516794685.gif" name="s_i_hphqglobal" border="0" height="1" width="1">
<!-- End SiteCatalyst code version: G.0. -->

<!--End Tag -->
</p></body></html>