<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML ><HEAD ><TITLE >sg changes</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="The Linux 2.4 SCSI subsystem HOWTO" HREF="index.html"><LINK REL="UP" TITLE="Changes between lk 2.2 and (during) 2.4" HREF="changes.html"><LINK REL="PREVIOUS" TITLE="st changes" HREF="chgst.html"><LINK REL="NEXT" TITLE="Changes during the lk 2.4 series" HREF="chg24.html"></HEAD ><BODY CLASS="sect1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >The Linux 2.4 SCSI subsystem HOWTO</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="chgst.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Appendix B. Changes between lk 2.2 and (during) 2.4</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="chg24.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="sect1" ><H1 CLASS="sect1" ><A NAME="chgsg" ></A >B.5. sg changes</H1 ><P > The main change is the addition of a new interface structure called "sg_io_hdr". The existing interface structure (called "sg_header") was found to be inflexible requiring the concatenation of raw data together with meta-data in the read() and write() commands. <TABLE BORDER="0" BGCOLOR="#E0E0E0" WIDTH="100%" ><TR ><TD ><FONT COLOR="#000000" ><PRE CLASS="programlisting" > sg_io_hdr {new interface structure} SG_IO {new ioctl} direct IO {present but commented out, see ALLOW_DIO} procfs output {new information in /proc/scsi/sg directory} boot/module parameters {new} </PRE ></FONT ></TD ></TR ></TABLE > </P ><P > Up to 64 bytes of sense data can be obtained from the sg_io_hdr interface structure. Also a residual count associated with the data transfer is available (if the lower level driver supports it, if not the residual count will be 0). </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="chgst.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="chg24.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >st changes</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="changes.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Changes during the lk 2.4 series</TD ></TR ></TABLE ></DIV ></BODY ></HTML >