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NAME="SG_IO_HDR_T">Chapter 6. The sg_io_hdr_t structure in detail</H1
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>Table of Contents</B
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><DT
>6.1. <A
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>interface_id</A
></DT
><DT
>6.2. <A
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>dxfer_direction</A
></DT
><DT
>6.3. <A
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>cmd_len</A
></DT
><DT
>6.4. <A
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>mx_sb_len</A
></DT
><DT
>6.5. <A
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>iovec_count</A
></DT
><DT
>6.6. <A
HREF="x198.html"
>dxfer_len</A
></DT
><DT
>6.7. <A
HREF="x204.html"
>dxferp</A
></DT
><DT
>6.8. <A
HREF="x209.html"
>cmdp</A
></DT
><DT
>6.9. <A
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>sbp</A
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><DT
>6.10. <A
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>timeout</A
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><DT
>6.11. <A
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>flags</A
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><DT
>6.12. <A
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>pack_id</A
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><DT
>6.13. <A
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>usr_ptr</A
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><DT
>6.14. <A
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>status</A
></DT
><DT
>6.15. <A
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>masked_status</A
></DT
><DT
>6.16. <A
HREF="x285.html"
>msg_status</A
></DT
><DT
>6.17. <A
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>sb_len_wr</A
></DT
><DT
>6.18. <A
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>host_status</A
></DT
><DT
>6.19. <A
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>driver_status</A
></DT
><DT
>6.20. <A
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>resid</A
></DT
><DT
>6.21. <A
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>duration</A
></DT
><DT
>6.22. <A
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>info</A
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>The main control structure for the version 3 SCSI generic driver has
a struct tag name of "sg_io_hdr" and a typedef name of "sg_io_hdr_t".
The structure is shown in abridged form below. The "[i]" notation
indicates an input value while "[o]" indicates a value that is output.
The "[i->o]" indicates a value that is conveyed from input to output and
apart from one special case, is not used by the driver. The "[i->o]" members
are meant to aid an application matching the request sent to a write()
to the corresponding response received by a read(). For pointers the
"[*i]" indicates a pointer that is used for reading from user memory into
the driver, "[*o]" is a pointer used for writing, and "[*io]" indicates
a pointer used for either reading or writing.
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>typedef struct sg_io_hdr
{
int interface_id; /* [i] 'S' (required) */
int dxfer_direction; /* [i] */
unsigned char cmd_len; /* [i] */
unsigned char mx_sb_len; /* [i] */
unsigned short iovec_count; /* [i] */
unsigned int dxfer_len; /* [i] */
void * dxferp; /* [i], [*io] */
unsigned char * cmdp; /* [i], [*i] */
unsigned char * sbp; /* [i], [*o] */
unsigned int timeout; /* [i] unit: millisecs */
unsigned int flags; /* [i] */
int pack_id; /* [i->o] */
void * usr_ptr; /* [i->o] */
unsigned char status; /* [o] */
unsigned char masked_status;/* [o] */
unsigned char msg_status; /* [o] */
unsigned char sb_len_wr; /* [o] */
unsigned short host_status; /* [o] */
unsigned short driver_status;/* [o] */
int resid; /* [o] */
unsigned int duration; /* [o] */
unsigned int info; /* [o] */
} sg_io_hdr_t; /* 64 bytes long (on i386) */</PRE
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