<HTML ><HEAD ><TITLE >dxfer_len</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="The Linux SCSI Generic (sg) HOWTO" HREF="index.html"><LINK REL="UP" TITLE="The sg_io_hdr_t structure in detail" HREF="sg_io_hdr_t.html"><LINK REL="PREVIOUS" TITLE="iovec_count" HREF="x192.html"><LINK REL="NEXT" TITLE="dxferp" HREF="x204.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 SCSI Generic (sg) HOWTO</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x192.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 6. The sg_io_hdr_t structure in detail</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x204.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="AEN198">6.6. dxfer_len</H1 ><P > This is the number of bytes to be moved in the data transfer associated with the command. The direction of the transfer is indicated by 'dxfer_direction'. If 'dxfer_len' is zero then no data transfer takes place. <A NAME="AEN201" HREF="#FTN.AEN201" >[1]</A ></P ><P > If iovec_count is non-zero then 'dxfer_len' should be equal to the sum of iov_len lengths. If not, the minimum of the two is the transfer length. The type of dxfer_len is unsigned int.</P ></DIV ><H3 CLASS="FOOTNOTES" >Notes</H3 ><TABLE BORDER="0" CLASS="FOOTNOTES" WIDTH="100%" ><TR ><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="5%" ><A NAME="FTN.AEN201" HREF="x198.html#AEN201" >[1]</A ></TD ><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="95%" ><P >Some HBA - SCSI device combinations have difficulties with an odd valued dxfer_len . In some cases the operation succeeds but a DID_ERROR host status is returned. So unless there is a good reason, applications that want maximum portability should avoid an odd valued dxfer_len .</P ></TD ></TR ></TABLE ><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="x192.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="x204.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >iovec_count</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="sg_io_hdr_t.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >dxferp</TD ></TR ></TABLE ></DIV ></BODY ></HTML >