chatr(1)chatr(1)NAMEchatr - change program's internal attributes
SYNOPSISchatr [+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)