unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (OSF1-V5.1-alpha)
Page:
Section:
Apropos / Subsearch:
optional field



sys_attrs_generic(5)					 sys_attrs_generic(5)



NAME

  sys_attrs_generic - system attributes	for the	generic	kernel subsystem

DESCRIPTION

  This reference page describes	the attributes for the Generic (generic) ker-
  nel subsystem. See sys_attrs(5) for general information about	setting	sys-
  tem attributes.



  act_vers_high
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  act_vers_low
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  binlog_buffer_size
      The kernel buffer	size in	bytes.

      Default value: If	the binlog_buffer_size is not explicitly specified,
      the value	for kernel buffer size is assigned at boot time	and is based
      on the amount of physical	memory installed on the	system.	The value
      assigned automatically ranges from 32 kilobytes to 1 megabyte.

      Minimum value: 8192 (bytes, or 8 KB)

      Maximum value: 1,048,576 (bytes, or 1 MB)



  booted_args
      The arguments that are passed from osf_boot to the kernel. This attri-
      bute value is query only.



  booted_kernel
      The name of the kernel that was loaded by	osf_boot. This attribute
      value is query only.



  clu_active_member
      A	value that indicates whether the system	is (1) or is not (0) an
      actively running member system in	a TruCluster environment. This
      query-only value is always set to	0 for a	standalone system.



  clu_configured
      A	value that indicates whether cluster kernel components are (1) or are
      not (0) configured in the	kernel.	This query-only	value is always	set
      to 0 for a standalone system.



  compressed_dump
      A	value that enables (1) or disables (0) a compressed dump file. The
      type of zero compression implemented for compression saves substantial
      disk space but still allows the dump to be read by dbx and other
      operating	system tools.  See expected_dump_compression for information
      about setting the	compression level.

      Default value: 1 (enabled)

      You might	want to	change the default value if you	consistently use
      tools, such as those from	a third	party, that do not support compressed
      dump files.  See the System Administration and the Kernel	Debugging
      manuals for more information about generating and	working	with dump
      files.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  cpu_enable_mask
      A	value for the bit mask that determines which CPUs are started in a
      multiprocessor system.  The lowest order bit (bit	0) in this mask
      corresponds to CPU0. The next highest order bit corresponds to CPU1,
      and so on, up to bit 63. The bits	in these positions can be set to 0
      (disabled) or 1 (enabled)	for the	corresponding CPU slots. The decimal
      or hexadecimal value specified for cpu_enable_mask corresponds to	the
      binary value that	has 0 and 1 in the correct ordinal positions for the
      CPUs you want to enable or disable.

      Default value: The hex value corresponding to the	slots of CPUs that
      are actually enabled. On single-CPU systems with the CPU in slot 0, the
      default value is 0x1.

      Minimum value: 0

      Maximum value: 0xffffffffffffffff	(or -1)

      Specifying -1 for	this attribute means that all CPUs present in the
      system are allowed to be started by the master CPU. Specifying 0 for
      this attribute enables uniprocessor operation in a multi-CPU system.
      Other values enable and disable specific CPUs, depending on what the
      system supports.

      The following table illustrates the relationships	between	bit settings
      and cpu_enable_mask values for enabling a	single CPU. It is generally
      easier to	determine and enter hexadecimal	values,	so only	a few signi-
      ficant decimal equivalents are shown:


		      Bit	     Dec.   Hex			Single
	   63... 8 7 6 5 4 3 2 1 0   Value  Value		CPU Enabled
	   ______________________________________________________________________
	   0 ... 0 0 0 0 0 0 0 0 0   0	    0			Special	meaning	*
	   0 ... 0 0 0 0 0 0 0 0 1   1	    0x1			CPU0
	   0 ... 0 0 0 0 0 0 0 1 0	    0x2			CPU1
	   0 ... 0 0 0 0 0 0 1 0 0	    0x4			CPU2
	   0 ... 0 0 0 0 0 1 0 0 0	    0x8			CPU3
	   0 ... 0 0 0 0 1 0 0 0 0	    0x10		CPU4
	   0 ... 0 0 0 1 0 0 0 0 0	    0x20		CPU5
	   0 ... 0 0 1 0 0 0 0 0 0	    0x40		CPU6
	   0 ... 0 1 0 0 0 0 0 0 0	    0x80		CPU7
	   0 ... 1 0 0 0 0 0 0 0 0	    0x100		CPU8
	      .
	      .
	      .
	   1 ... 0 0 0 0 0 0 0 0 0	    0x8000000000000000	CPU63

      *	The minimum value (0) indicates	that only the master (boot) CPU	be
      enabled. This value is useful if you want	to test	applications in	a
      uniprocessor environment and your	test system normally runs in mul-
      tiprocessor mode.


				       Note

	 Some systems require that the master CPU be CPU0. For these systems,
	 0, 1, and 0x1 are equivalent entries and are the only values you
	 should	specify	for uniprocessor operation. On these systems, 0x1 is
	 always	the value set for cpu_enable_mask because the kernel  will
	 overwrite values specified for	cpu_enable_mask	that are incompatible
	 with having CPU0 as the master	CPU. For other systems,	users can
	 choose	the slot position of the master	CPU. Therefore,	the result of
	 entering 0 for	this attribute can vary. For example, the actual set-
	 ting would be 0x2 if CPU1 were	the master CPU and 0x10	if CPU4	were
	 the master CPU.

      The following table illustrates the relationships	between	bit settings
      and cpu_enable_mask values for enabling sample combinations of CPUs:


		      Bit	    Dec.   Hex		       Multiple
	   63... 8 7 6 5 4 3 2 1 0  Value  Value	       CPUs Enabled
	   _________________________________________________________________________
	   0 ... 0 0 0 0 0 0 0 1 1	   0x3		       CPU0, CPU1
	   0 ... 0 0 0 0 0 0 1 0 1	   0x5		       CPU0, CPU2
	   0 ... 0 0 0 0 0 0 1 1 0	   0x6		       CPU1, CPU2
	   0 ... 0 0 0 0 0 0 1 1 1	   0x7		       CPU0, CPU1, CPU2
	      .
	   0 ... 0 0 0 0 0 1 1 1 1	   0xf		       CPU0 to CPU3
	      .
	   0 ... 0 0 0 0 1 1 1 1 1	   0x1f		       CPU0 to CPU4
	      .
	   0 ... 0 0 0 1 1 1 1 1 1	   0x3f		       CPU0 to CPU5
	      .
	   0 ... 0 0 1 1 1 1 1 1 1	   0x7f		       CPU0 to CPU6
	      .
	   0 ... 0 1 1 1 1 1 1 1 1	   0xff		       CPU0 to CPU7
	      .
	   0 ... 1 1 1 1 1 1 1 1 1	   0x1ff	       CPU0 to CPU8
	      .
	      .
	      .
	   1 ... 1 1 1 1 1 1 1 1 1  -1	   0xffffffffffffffff  All available CPUs *

      *	The maximum value specifies 1 in all bit positions, thereby enabling
      all available CPUs. This value corresponds to 18446744073709551615 or
      -1 in decimal notation and 0xffffffffffffffff in hexadecimal notation.

      You can enable and disable specific combinations of CPUs by entering
      values that set and clear	appropriate bit	positions in the bit mask. If
      you suspect that one of the CPUs on a multiprocessor system may be the
      cause of a system	problem, you can try running the system	with dif-
      ferent combinations of available CPUs disabled to	help confirm your
      suspicion. Remember that if your system is one of	those that require
      CPU0 to be the master CPU, the kernel does not apply values that map to
      0	in bit position	0. In this case, you have to switch another CPU	into
      slot 0 before you	can do a test run that disables	the CPU	originally in
      slot 0.

      Certain lockmode attribute values	override incompatible cpu_enable_mask
      settings.	 If the	value of the lockmode attribute	is 0 or	1, all bits
      in the cpu_enable_mask bit mask that do not correspond to	the master
      CPU are set to 0.



  * dump_exmem_addr
      Identifies the starting address (virtual or physical) for	a region of
      exempt memory to be used for writing primary system core dumps. The
      specified	address	must be	page aligned.

      Default value: 0 (disables writing the dump to an	exempt memory region)

      This attribute can be set	at run time. The setting of dump_exmem_addr
      has no effect unless the dump_exmem_size attribute is also set to
      specify the size of the exempt memory region to contain the dump.	If
      you decide to write system core dumps to a region	of exempt memory,
      make sure	you keep a record of any run-time settings for
      dump_exmem_addr and dump_exmem_size so you will be able to find a	crash
      dump after recovery from a system	failure.

      The dump_exmem_addr and dump_exmem_size attributes have no effect	if
      the setting of the dump_to_memory	attribute disables writing of dumps
      to memory	or if the setting of the dump_savecnt attribute	disables
      writing of dumps altogether.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * dump_exmem_include
      Determines whether exempt	memory pages are included (1) or not included
      (0) in the system	core dump.

      Default value: 0 (exempt memory pages are	not included in	the dump)

      This attribute can be set	at run time.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * dump_exmem_size
      Specifies	the size (in bytes) of the exempt memory region	to which sys-
      tem core dumps are written. This value must be a multiple	of the
      machine word size.

      Default value: 0 (disables writing the dump to an	exempt memory region)

      This attribute can be set	at run time. The setting of this attribute
      has no effect unless the dump_exmem_addr attribute is also set to
      specify the starting address for the region being	sized. The descrip-
      tion of dump_exmem_addr discusses	additional attribute dependencies.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * dump_kernel_text
      Enables or disables the inclusion	of kernel text pages. This attribute
      only applies when	partial	dumps are enabled (see partial_dump and
      dump_savecnt). Dumped kernels will be larger.

      Default value: 0 (disabled)

      Minimum value: 0 (disabled)

      Maximum value: 1 (enabled)

      This value can be	changed	at run time.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * dump_savecnt
      A	value that limits the number of	successful crash dumps that are	gen-
      erated for a single crash/reboot sequence. Valid values are:

      0	      Never generate a crash dump

      1	      Generate a primary crash dump (the default)

      2	      Generate a secondary crash dump

	      A	secondary fault	can occur on system failure, in	which case, a
	      secondary	crash dump is generated	in addition to the primary
	      crash dump. The secondary	crash dump is always written to	non-
	      exempt memory. See the entry for the dump_to_memory attribute
	      for information that also	has impact on whether a	secondary
	      dump is produced and whether it overwrites the primary dump.

      System core dumps	provide	critical troubleshooting information to	your
      support representative. Although the default value of the	dump_savecnt
      attribute	can be changed at run time, do so only under direction of
      your support representative.

      See the entries for other	dump_* attributes and the compressed_dump,
      expected_dump_compression, partial_dump, and live_dump_* attributes for
      information about	controlling where system dumps are written, whether
      dumps are	compressed (and	at which level), and the amount	and type of
      information that dumps include.  In general, changes to any of these
      attributes are best done under the guidance of your support representa-
      tive.

      See the Kernel Debugging and the System Administration manuals for more
      information about	creating and working with dump files.



  * dump_sp_threshold
      A	threshold size that determines whether single-partition	or multiple-
      partition	dumps are created. If a	dump will fit on the primary swap
      partition	and leave space	that is	equal to this threshold	value, the
      dump is created as a single-volume dump on the primary swap partition,
      even if secondary	swap partitions	are available. (See the	System
      Administration and the Kernel Debugging manuals for details.)

      Default value: 16,384

      Minimum value: 0

      Maximum value: 2,147,483,647

      This value can be	changed	at run time.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * dump_to_memory
      A	value that controls whether primary system core	dumps are written to
      memory or	disk.  This attribute can have the following values:

      -1      Dumps are	written	only to	disk; writing dumps to memory is dis-
	      abled. This value	also disables writing a	secondary dump (when
	      dump_savecnt is equal to 2).

      0	(zero)
	      Dumps are	written	to disk	except in the event of disk failure,
	      in which case they are written to	memory.	This is	the default
	      behavior.

      1	      Dumps are	written	only to	memory when sufficient memory is
	      available; otherwise, a disk dump	might be generated. See	the
	      following	discussion if primary and secondary dumps are both
	      enabled (when dump_savecnt is equal to 2).

      The dump_to_memory value can be changed at run time; however, do so
      only under direction of your support representative.

      By default, a primary system crash dump that is written to memory
      (dump_to_memory is set to	1) occupies non-exempt memory. If the
      dump_savecnt attribute is	set to 2 (to enable a secondary	crash dump),
      the secondary dump is also written to non-exempt memory. Therefore,
      setting dump_savecnt to 2	and dump_to_memory to 1	will cause the secon-
      dary dump	to clobber the primary dump. If	you want to enable both	a
      primary and a secondary crash dump and have both dumps available in
      memory, you can work around this problem by writing the primary dump to
      exempt memory. See the dump_exmem_addr and dump_exmem_size attributes
      for information about writing primary memory dumps to exempt memory
      rather than non-exempt memory.

      See the dump_savecnt attribute for information about disabling the
      writing of system	core dumps altogether and for cross-references to
      other dump-related attributes.



  dump_user_pte_pages
      A	value that enables (1) or disables (0) the inclusion of	user page
      table entries in a crash dump. Normally, user page table entries con-
      tribute no information about the cause of	a system crash.

      Default value: 0 (disabled)

      This value can be	changed	at run time. However, you would	normally
      change it	only when directed to do so by a support representative	who
      is gathering information about a particular problem.



  * enable_async_printf
      A	value that enables (1) or disables (0) asynchronous printing of	mes-
      sages to the console. Asynchronous printing to the console prevents
      large numbers of messages	from being written to the console at the same
      time.

      Default value: 1 (enabled)

      This value can be	changed	at run time. Device driver developers need to
      set enable_async_printf to 0 when	debugging driver problems because
      they need	to see the results of kernel printf() calls at the time	of
      execution.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * expected_dump_compression
      The level	of compression that a dump is typically	expected to achieve.

      Default value: 500

      Minimum value: 0

      Maximum value: 1000

      This value can be	changed	at run time. See the System Administration
      manual for instructions on how to	calculate the typical dump compres-
      sion level for your system.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * insecure_bind
      A	value that allows programmers to override file permissions when	UNIX
      domain sockets are created by a bind() call.

      When insecure_bind is set	to a value other than 0, UNIX domain sockets
      are always created with mode 0777	(the umask is ignored).	 This
      prevents bind: permission	denied errors when the bind() call executes.

      Default value: 0,	meaning	that file permission (umask) is	not ignored

      This value can be	changed	at run time. See bind(2) for more information
      about creating domain sockets.

      In a TruCluster environment, the value of	this attribute must be the
      same on all member systems.



  kmem_audit_count
      See kmem_debug.



  kmem_debug
      A	value that enables (1) or disables (0) behavior	useful for debugging
      problems in kernel memory	allocation.

      Default value: 0

      If enabled (1), each time	the kernel memory allocator allocates or
      deallocates memory in the	kernel memory pool, the	system checks whether
      the operation is performed correctly. If the kernel memory pool is in a
      corrupt state, the system	crashes	and provides useful debugging infor-
      mation. This attribute, along with the kmem_audit_count,
      kmem_debug_size_mask, kmem_protected_kmempercent,	kmem_protected_lowat,
      kmem_protected_size, and a series	of kmemhighwater_* attributes should
      be set only by or	under the direction of kernel software developers or
      support personnel.



  kmem_debug_size_mask
      See kmem_debug.



  kmem_percent
      The maximum percentage of	kernel virtual address space that is reserved
      for kernel memory	allocator (malloc) memory.

      Default value: 25	(percent)

      Minimum value: 0

      Maximum value: 100

      If this value is too low,	no space in map	errors may occur and cause
      the system to hang. However, this	situation indicates an unexpected
      problem that should be reported to your support representative.  Do not
      modify the default value for kmem_percent	unless directed	to do so by
      your support representative.



  kmem_protected_hiwat
      See kmem_debug.



  kmem_protected_kmempercent
      See kmem_debug.



  kmem_protected_lowat
      See kmem_debug.



  kmem_protected_size
      See kmem_debug.



  kmemhighwater_*
      See kmem_debug.



  * kmemreserve_percent
      The percentage of	memory that is reserved	for the	malloc component and
      used for kernel memory allocations that are less than or equal to	the
      page size	(8 KB).

      Default value: 0,	which actually specifies 0.4 percent of	available
      memory or	256 KB,	whichever is smaller.

      Minimum value: 1

      Maximum value: 75

      A	heavy network load that	results	in dropped packets is the primary
      reason why you might want	to increase the	kmemreserve_percent value.
      The netstat -d -i	or the vmstat -M command shows you whether there are
      dropped packets. Increase	the kmemreserve_percent	value in small incre-
      ments until there	are no entries in the fail_nowait column of the
      vmstat -M	command's output display.

      This value can be	modified at run	time. However, once the	value has
      been increased, you cannot decrease it below 1 percent at	run time. To
      restore the default setting (which is calculated by the kernel), you
      must directly edit the /etc/sysconfigtab file to remove or comment out
      the attribute and	then reboot the	system.	This restriction will be
      removed in a future release. (Under ordinary conditions, direct editing
      of the /etc/sysconfigtab file is a practice that is strongly
      discouraged.)



  lite_system
      A	setting	that enables (1) or disables (0) a set of attribute values
      that improve performance for 32-MB systems.  This	attribute will soon
      be obsolete. Most	kernel components now determine	memory size directly
      and apply	more sophisticated algorithms to determine defaults best
      suited for the system.

      Default value: 1 if memory size is less than or equal to 32 MB and 0 if
      memory size is greater than 32 MB

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  * live_dump_dir_name
      The full path to the directory where live	dumps are written. This
      attribute	allows you to write dumps generated while the system is	run-
      ning to a	directory other	than the one where crash dumps are written.

      Default value: /var/adm/crash (same directory as used for	crash dumps)

      Minimum string length: 1 (byte)

      Maximum string length: 65	(bytes)

      This value can be	modified at run	time.

      See the dump_savecnt entry for overview information about	dump-related
      attributes.



  * live_dump_zero_suppress
      A	value that enables (1) or disables (0) zero compression	of dumps that
      are generated while the system is	still running. The zero	compression
      process produces files that take longer to create	but occupy less	space
      on disk.

      Default value: 1 (enabled)

      This value can be	modified at run	time. You might	want to	set this
      value to 1 if you	consistently use tools,	such as	those from third par-
      ties, that do not	support	compressed dump	files or you want dumps
      created in a minimum amount of time. Because the system is still run-
      ning while a live	dump is	being created, some of the data	in a live
      dump may be inconsistent.	The shorter creation time may result in	less
      data inconsistency.

      See the dump_savecnt entry for overview information about	dump-related
      attributes. See the Kernel Debugging and the System Administration
      manuals for more information about creating and working with dump
      files.



  lockdebug
      A	value that enables (1) or disables (0) lock debugging. If enabled
      (1), the default value for the lockmode attribute	is set to 4.

      If you explicitly	specify	a value	for the	lockmode attribute, that
      value also causes	lockdebug to be	set or reset (overridden).  For	exam-
      ple, if you set lockmodeto be 0, 1, 2, or	3, the value of	lockdebug
      will be 0.  If you set lockmode to be 4, the value of lockdebug will be
      1.

      Default value: 0 (disabled)



  * lockmaxcycles
      Used for internal	debugging.

      Default value: 0

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  lockmode
      The mode in which	the lock package, simple (spin)	or queued, is used
      within the kernel. (See the discussion of	the locktype attribute for
      information about	the type of lock package used for different systems.)
      Mode settings, which apply to both lock packages,	support	different
      combinations of real-time	(RT) kernel preemption,	symmetric multipro-
      cessing (SMP), and lock debugging	with lock statistics:

      0	      Neither RT nor SMP is required.  In this case, the calls to the
	      lock primitives are patched out completely.

      1	      Only RT is required. In this case, the lock operations maintain
	      a	"preemption blocking" count.

      2	      Only SMP is required. In this case, the lock operations provide
	      synchronization among multiple CPUs.

      3	      Both RT and SMP are required.  In	this case, lock	operations
	      are performed as described for both mode 1 and 2.

      4	      Both RT and SMP are required.  In	this case, lock	operations
	      are as described for mode	3, with	the addition of	kernel lock
	      debugging	and statistics.

      Default value: Assigned at boot time, depending on the values for	the
      rt_preempt_opt, cpu_enable_mask, and lockdebug attributes, and on
      whether multiple CPUs are	able to	be booted.

      If you specify a value for lockmode (0-4), your setting both overrides
      the default setting and disables any of the three	related	capabilities
      that cannot be supported by the chosen set of lock primitives. For
      example, setting lockmode	to 0, 1, 2, or 3 disables kernel lock debug-
      ging and statistics, whether or not the lockdebug	attribute was origi-
      nally set	to 1 (to enable	kernel lock debugging and statistics).



  locktimeout
      The number of seconds that a CPU will wait on a lock. If a CPU cannot
      acquire a	lock in	the specified amount of	time, a	fatal error occurs,
      and the system panics and	issues a message that the lock time limit was
      exceeded.

      Default value: 15	(seconds)

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit instructions. A 0 value
      might cause boot failures	on a multiprocessor system. Values larger
      than the default might hang the system instead of	causing	it to panic
      and reboot.



  locktype
      A	value that specifies the type of locking package that the kernel
      software uses on the system. When	the value is 0,	simple (spin) locking
      is used. When the	value is 1, queued locking is used. (A value of	1 is
      ignored on non-NUMA platforms.)

      Default value: 1 on GS80,	GS160, and GS320 systems; otherwise, 0.

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit instructions.



  login_name_max
      The maximum number of bytes supported for	a user's login name string.
      One byte may be equivalent to one	character in many languages; however,
      byte-to-character	equivalence varies, depending on the user's default
      locale.

      Default value: 12	(bytes)

      Minimum value: 9

      Maximum value: 64

      In a TruCluster environment, the value of	this attribute must be the
      same on all member systems.

      The default 12-byte limit	exists only for	backward compatibility rea-
      sons. Increase login_name_max to 64 to enable longer login names.



  max_lock_per_thread
      The depth	to which complex locks can be nested for a thread at one
      time.  The value of max_lock_per_thread is used for debugging (when
      lockmode=4).

      Default value: 32

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  memberid
      Cluster member ID	that is	set only by TruCluster software.

      Default value: 0 (for standalone systems)

      Minimum value: 0

      Maximum value: 255



  memberseq
      Reserved for future use by TruCluster software.



  memlimit
      A	kernel debugging value intended	for internal use only.



  memstr_buf_size
      A	kernel debugging value intended	for internal use only.



  memstr_end_addr
      A	kernel debugging value intended	for internal use only.



  memstr_start_addr
      A	kernel debugging value intended	for internal use only.



  msgbuf_size
      The size (in bytes) of the message buffer	that is	used to	store boot
      log messages.

      Default value: Set automatically,	based on memory	size.

      Minimum value: 0 (bytes)

      Maximum value: 1,048,576

      You may need to increase this value on a large system that issues	too
      many boot	messages for the buffer	to hold	until the syslog daemon
      starts. If the buffer is too small, initial boot messages	are not	writ-
      ten to the system	log and	the beginning of the first message that	is
      written is likely	to be truncated.



  new_vers_high
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  new_vers_low
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  old_obreak
      A	value that changes the behavior	of an internal system call.

      Default value: 1 (on)

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation. Setting
      this value to off	(0) has	a negative impact on system performance.



  old_vers_high
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  old_vers_low
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  * partial_dump
      A	value that determines whether the system generates partial (1) or
      full (0) crash dumps when	crash dumps are	enabled.

      Default value: 1 (partial	dumps are created)

      You can modify this attribute at run time. See the entry for the
      dump_savecnt attribute for general information about dump-related
      attributes.



  * physio_max_coalescing
      A	value that controls how	I/O requests are gathered when readv or	wri-
      tev operations are directed at a character device	(not a block device).
      For example, when	set to 262,144,	up to 32 8-KB buffers coalesce into
      one 256-KB buffer.  This improves	the efficiency of database opera-
      tions.

      Default value: 262,144

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  replicate_text
      A	value that controls whether kernel text	can or cannot be replicated
      on multiple CPUs of a NUMA-enabled system	(GS80, GS160, GS320). When
      the value	is 1, replication of kernel text is enabled. When the value
      is 0, replication	of kernel text is disabled. This attribute is some-
      times used by kernel developers when debugging software for NUMA-
      enabled systems; however,	the attribute is not for general use. (The
      value must be 0 on non-NUMA systems and changing it to 0 on NUMA sys-
      tems will	degrade	performance.)

      Default value: 1,	on a NUMA-enabled system; otherwise, 0.

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  rolls_ver_lookup
      A	value that is set and used internally to support a rolling upgrade
      operation	in a TruCluster	environment. Do	not modify manually.



  rt_preempt_opt
      A	value that enables (1) or disables (0) real-time kernel	preemption.

      Default value: 0 (disabled)

      If real-time kernel preemption is	enabled	(1):

	+  The default value for lockmode will be 1 on a single-CPU system or
	   3 on	a multi-CPU system.  However, if you explicitly	specify	cer-
	   tain	lockmode values, you implicitly	override the rt_preempt_opt
	   value. For example, if you set lockmode to 0	or 2, you implicitly
	   set rt_preempt_opt to 0, disabling real-time	kernel preemption.

	+  The default value for ufs_lockholdmax will be 50. See
	   sys_attrs_ufs(5) for	information on ufs_lockholdmax.



  * use_faulty_fpe_traps
      A	value that restores (1)	or corrects (0)	backward-compatible but
      incorrect	behavior by the	kernel's IEEE handler with respect to fast
      mode floating-point exception traps.

      When use_faulty_fpe_traps	is set to 0, the IEEE handler correctly
      returns a	*_TRAP code for	imprecise or invalid traps that	cannot be
      resolved and re-executed.

      When use_faulty_fpe_traps	is set to 1, the IEEE handler reverts to
      returning	a *_FAULT code for faulty traps	that cannot be fixed and re-
      executed.	However, *_FAULT codes should be returned only when the
      trap's trigger PC	and instructions can still be determined; otherwise,
      re-execution cannot be completed.

      See ieee(3) and the Alpha	Architecture Reference Manual for more infor-
      mation on	this topic.

      Default value: 0 (correct	return of *_TRAP code for faulty traps that
      cannot be	resolved and re-executed)

      It is strongly recommended that you do not modify	the default value.



  * user_cfg_pt
      The CFG run-time points that are configurable from user mode. Setting
      this attribute to	a particular value triggers kernel callbacks that
      have been	registered for the point corresponding to that value.

      Default value: 45,000

      Do not modify the	default	setting	for this attribute unless instructed
      to do so by support personnel or by patch	kit documentation.



  version
      The version string value (maximum	length of 256 bytes) that is set at
      kernel configuration time	by the operating system	software and returned
      by the sizer -v command. For example:


	   Compaq Tru64	UNIX V5.1 (Rev.	732); Mon Feb  5 15:32:40 EST 2001



  version_avendor
      The string value (maximum	length of 32 bytes) that is set	at kernel
      configuration time by the	operating system software to specify the
      abbreviated vendor name. For example:


	   COMPAQ



  version_banner
      The string value (maximum	length of 64 bytes) that is set	at kernel
      configuration time by the	operating system software to specify the pro-
      duct banner. For example:


	   Compaq Tru64	UNIX



  version_product
      The string value (maximum	length of 32 bytes) that is set	at kernel
      configuration time by the	operating system software to specify the pro-
      duct name. For example:


	   Tru64 UNIX



  version_release
      The string value (maximum	length of 64 bytes) that is set	at kernel
      configuration time by the	operating system software to specify the pro-
      duct release. For	example:


	   V5.1	(Rev. 732)



  version_vendor
      The string value (maximum	length of 128 bytes) that is set at kernel
      configuration time by the	operating system software to specify the full
      vendor name. For example:


	   Compaq Computer Corporation



SEE ALSO

  Commands: dxkerneltuner(8), sysconfig(8), sysconfigdb(8)

  Others: sys_attrs(5)

  System Configuration and Tuning


  System Administration

  Kernel Debugging