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SYSGET(2)							     SYSGET(2)

NAME    [Toc]    [Back]

     sysget - Call for reading or writing kernel data

SYNOPSIS    [Toc]    [Back]

     #include <sys/sysget.h>

     sysget (int name, char *buffer, int buflen, int flags,
     sgt_cookie_t *cookie);

DESCRIPTION    [Toc]    [Back]

     The sysget	system call provides user access to kernel structures and
     tables on IRIX systems. sysget can	return data for	a combination of cpus,
     nodes, or cells depending on the combination of flags and cookie

     The sysget	system call accepts the	following arguments:

     name    Identifies	the kernel structure or	table. The sys/sysget.h	file
	     contains the list of names	supported. Most	come from the sysmp
	     MP_SAGET options.	Here is	a partial list:

	     SGT_SINFO	  SGT_MINFO SGT_DINFO SGT_SERR Returns the various
			  sysinfo-type structures. See the sys/sysinfo.h file.

	     SGT_RMINFO	  Returns the rminfo structure.	See the	sys/sysmp.h

			  Returns the nodeinfo structure for each node.	See
			  the sys/sysinfo.h file.

	     SGT_KSYM	  Returns the structure	identified by the kernel
			  symbol specified in the cookie by using the
			  SGT_COOKIE_SET_KSYM()	macro. Only a subset of	kernel
			  symbols are supported. See the sys/sysget.h file.

     buffer  Points to the user's buffer space.

     buflen  Specifies the size	of buffer in bytes.

     flags   Specifies option flags.  A	user must select the SGT_INFO,
	     SGT_READ, or SGT_WRITE flag.  flags is combination	of one or more
	     of	the following:

	     SGT_INFO	  Returns information on the kernel structure or table
			  defined by the name argument.	This option is similar
			  to the sysmp MP_SASZ option.	The buffer argument
			  points to a structure	defined	in the sys/sysget.h
			  file as the following:

			   struct sgt_info {
				 int	  si_size;

									Page 1

SYSGET(2)							     SYSGET(2)

				 int	  si_num;
				 int	  si_hiwater;

	     SGT_READ	  Returns the information defined by the name argument
			  in the buffer	specified by the buffer	argument.

	     SGT_STAT	  Returns information about the	table or server
			  specified by the name	argument. This information is
			  similar to that provided by the SGT_INFO flag.

	     SGT_SUM	  This flag is obsolete	and will be ignored.

	     SGT_WRITE	  Writes the information specified by the buffer
			  argument to the kernel structure defined by the name

	     SGT_CPUS	  Returns data for each	cpu. Not all structures
			  support this option.

	     SGT_NODES	  Returns data for each	node. Not all structures
			  support this option.

     cookie  Specifies which cell, cpu,	or node	should be used when asking for
	     information.  The kernel also uses	it as a	place-holder mechanism
	     to	allow sysget to	be used	iteratively to return a	list of
	     structures	when the length	of the list is unknown.	Other uses are
	     to	specify	a specific location to seek to in a list.

	     This argument points to a structure defined as follows:

	      struct sgt_cookie	{
		     sc_status_t    sc_status;
		     union {
			     cell_t	     cellid;
			     cnodeid_t	     cnodeid;
			     int	     cpuid;
		     } sc_id;
		     sc_type_t	     sc_type;
		     char	     sc_opaque[SGT_OPAQUE_SZ];

	     The cookie	must be	initialized before the first call by using the
	     SGT_COOKIE_INIT() macro.  See the sys/sysget.h file

RETURN VALUES    [Toc]    [Back]

     If	sysget completes normally, the number of bytes copied is returned,
     otherwise a value of -1 is	returned and errno is set to indicate the

									Page 2

SYSGET(2)							     SYSGET(2)

ERRORS    [Toc]    [Back]

     The sysget	system call fails if one of the	following error	conditions

     Error Code		 Description

     EFAULT		 The buffer address specified is not valid.

     EINVAL		 A flag	was specified in a context that	was not	valid
			 or the	cookie was not set properly.

     ENOENT		 The value specified in	the name argument or in
			 combination with the cookie is	unknown.

     ENOTSUP		 The function specified	by the flags parameter is not

     ESRCH		 The cookie or cpu specified is	not valid.

EXAMPLES    [Toc]    [Back]

     The following examples show how to	use the	sysget system call to retrieve

     Example 1:	 This example shows how	to use sysget to obtain	the number and
     size of sysinfo structures	in the system (a system	running	cells will
     have a sysinfo structure per cell):

	sgt_info_t info;
	sgt_cookie_t cookie;

	sysget(SGT_SINFO, (char	*)&info, sizeof(info),
		SGT_INFO, &cookie);
	printf("number of sysinfo: %d, size: %d\n",
		info.si_num, info.si_size);

     Example 2:	 In this example, sysget reads the list	of sysinfo structures
     for each cpu:

	sgt_info_t info;
	sgt_cookie_t cookie;
	struct sysinfo *si;

	sysget(SGT_SINFO, (char	*)&info, sizeof(info),
		SGT_INFO | SGT_CPUS, &cookie);

	si = (struct sysinfo *)malloc(info.si_num * info.si_size);

	sysget(SGT_SINFO, (char	*)si, info.si_num * info.si_size,
		SGT_READ | SGT_CPUS, &cookie);

									Page 3

SYSGET(2)							     SYSGET(2)

     Example 3:	 In this example, sysget reads the list	of sysinfo structures
     for each cpu one at a time	by iterating on	the cookie:

	sgt_info_t info;
	sgt_cookie_t cookie;
	struct sysinfo si;

	while (cookie.sc_status	!= SC_DONE) {
	       sysget(SGT_SINFO, (char *)&si, sizeof(si),
		   SGT_READ | SGT_CPUS,	&cookie);

     Example 4:	 This example shows how	to use sysget to read the contents of
     a structure by specifying its kernel symbol using the SGT_KSYM option:

	sgt_cookie_t cookie;
	int avenrun[3];

	SGT_COOKIE_SET_KSYM(&cookie, "avenrun");
	sysget(SGT_KSYM, (char *)avenrun, sizeof(avenrun),
		SGT_READ, &cookie);

SEE ALSO    [Toc]    [Back]

     sysmp(2), syssgi(2), nlist(3C), sysctl(3C)

									PPPPaaaaggggeeee 4444
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