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chatr(1)							      chatr(1)

NAME
       chatr - change program's internal attributes

SYNOPSIS
       chatr [+ed flag] file... [+bp flag] [value] [+l3 flag]

OPTIONS
       Change  the  program  attribute	that enables user code to execute from
       data (stack or heap). The flag values are enable and disable to	change
       this  attribute.	  Tune	binary files for properties different from the
       system-wide big page memory allocation settings.	 This allows for  more
       flexible performance tuning.  Enable big pages using any big pages tun‐
       ing parameters previously set with  the	chatr  utility.	  Disable  big
       pages  using  any  big  pages tuning parameters previously set with the
       chatr utility.  Use system-wide setting for big	pages  using  any  big
       pages tuning parameters set with the chatr utility.  Allow big pages to
       distribute memory across RADs as a priority over	 getting  the  largest
       page size possible.

	      Default value: 1 (Use smp)

	      Setting the value to 0 enables this feature.  The minimum amount
	      of anonymous memory  (in	Kbytes)	 that  a  user	process	  must
	      request before the kernel will map a virtual page in the process
	      address space to more than one physical page.  Anonymous	memory
	      is   requested  by calls to mmap(), nmmap(), malloc(), and amal‐
	      loc().

	      Default value: 64 (Kbytes)

	      Minimum value: 0 (big pages allocation mode disabled for	anony‐
	      mous memory)

	      Setting  the value to 0 or -1 causes the value to be set to sys‐
	      tem-wide value.  The minimum amount of memory (in Kbytes) that a
	      user  process  must request for a program text object before the
	      kernel will map a virtual page in the process address  space  to
	      more  than  one  physical	 page.	Allocations  for  program text
	      objects are generated when the process  executes	a  program  or
	      loads a shared library.

	      Default value: 64 (Kbytes)

	      Minimum  value: 0 (big pages memory allocation disabled for pro‐
	      gram text objects)

	      Setting the value to 0 or -1 causes the value to be set to  sys‐
	      tem-wide	value.	 The  minimum amount of System V shared memory
	      (in Kbytes) that a user process must request before  the	kernel
	      will  map	 a  virtual  page in the process address space to more
	      than one physical page.

	      Default value: 64 (Kbytes)

	      Minimum value: 0 (big pages memory allocation disabled for  pro‐
	      gram text objects)

	      Setting  the value to 0 or -1 causes the value to be set to sys‐
	      tem-wide value.  The minimum amount  (in	Kbytes)	 of  segmented
	      shared  memory  (System V shared memory with shared page tables)
	      that a user process must request before the kernel  will	map  a
	      virtual page in the process address space to more than one phys‐
	      ical page.

	      Default value: 64 (Kbytes)

	      Minimum value: 0 (big pages memory allocation disabled for  pro‐
	      gram text objects)

	      Setting  the value to 0 or -1 causes the value to be set to sys‐
	      tem-wide value.  The minimum amount of memory (in Kbytes) needed
	      for  the user process stack before the kernel will map a virtual
	      page in the process address space	 to  more  than	 one  physical
	      page.

	      Default value: 64 (Kbytes)

	      Minimum  value: 0 (big pages memory allocation disabled for pro‐
	      gram text objects)

	      Setting the value to 0 or -1 causes the value to be set to  sys‐
	      tem-wide value.

	      enable Enable big pages Tune binary files for properties differ‐
	      ent from the system-wide level3 granularity (l3gh).  This allows
	      for  more flexible performance tuning.  Disable level 3 granual‐
	      rity hints.  Enable level 3 granularity hints  using  parameters
	      previously  set with the chatr utility.  Use system-wide setting
	      for level 3 granularity hints.  Enable level 3 granularity hints
	      in  anonymous memory. Anonymous memory is	 requested by calls to
	      mmap(), nmmap(), malloc(), and amalloc().

	      Setting the value to any non-zero value  enables	this  feature.
	      Setting the value to zero disables it.  Enable level 3 granular‐
	      ity hints in System V shared memory

	      Setting the value to any non-zero value  enables	this  feature.
	      Setting the value to zero disables it.  Enable level 3 granular‐
	      ity hints in segmented shared memory  (System  V	shared	memory
	      with shared page tables).

	      Setting  the  value  to any non-zero value enables this feature.
	      Setting the value to zero disables it.

DESCRIPTION
       The chatr command changes a program's internal attributes.   Upon  com‐
       pletion, chatr prints the file's old and new values to standard output.

       The  +ed	 option	 of  chatr is used to specify that a particular binary
       must be able to execute from its stack or heap, regardless of the  sys‐
       tem default setting. This allows a restrictive system default while not
       preventing legitimate programs from executing  code  in	data.  Ideally
       this  option  should  be	 set (if needed) by the program's provider, to
       minimize the need for manual intervention by system administrators.

RESTRICTIONS
       The chatr command can only be used to modify  the  attributes  of  exe‐
       cutable	object	files,	and  shared  libraries.	 It  does  not support
       archived libraries, or object files that have been relocated.

ENVIRONMENT VARIABLES
       The following environment variables affect the execution of  the	 chatr
       command:	 Provides  a  default value for the internationalization vari‐
       ables that are unset or null. If LANG is unset or null, the correspond‐
       ing value from the default locale is used. If any of the international‐
       ization variables contain an invalid setting, the utility behaves as if
       none  of	 the variables had been defined.  If set to a non-empty string
       value, overrides the values of all the other internationalization vari‐
       ables.	Determines  the	 locale for the interpretation of sequences of
       bytes of text data as characters (for example, single-byte  as  opposed
       to  multi-byte characters in arguments).	 Determines the locale for the
       format and contents of diagnostic messages written to  standard	error.
       Determines  the	location  of  message catalogues for the processing of
       LC_MESSAGES.

SEE ALSO
       Functions: mmap(2)

								      chatr(1)
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