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Full Discussion: Why cant p show the values of some varialbes?
Top Forums Programming Why cant p show the values of some varialbes? Post 302274089 by Corona688 on Tuesday 6th of January 2009 03:53:01 PM
Old 01-06-2009
"Value optimized out" is when the compiler assumes a value is constant and starts hardcoding it instead of reading it from memory. For example:

Code:
int main(void)
{
  int x=5, y=1, z;
  for(z=0; z<10; z++)
  {
    y=y+x;
  }
}

The compiler can see that nothing else ever assigns a value to x, and if told to optimize the code, will assume it to be a constant value. Knowing this, the compiler may create code like ADD $Y, 5 instead of ADD $Y, $X which has the advantage of not needing to read the value of X from memory every loop.

Having gone this far it may decide that there's no reason for x to actually exist at all, and remove it. Hence value optimized out. Even if it does leave it around you may be in for a suprise when you poke in changes with your debugger; this hardcoded optimization would ignore it.

So it may be that trying to debug an optimized executable is causing all this missingness. Try recompiling with -O0 and see if anything comes back.
 

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LEARN ABOUT CENTOS

secon

SECON(1)								NSA								  SECON(1)

NAME

       secon - See an SELinux context, from a file, program or user input.

SYNOPSIS

       secon [-hVurtscmPRfLp] [CONTEXT]
       [--file] FILE
       [--link] FILE
       [--pid] PID

DESCRIPTION

       See a part of a context. The context is taken from a file, pid, user input or the context in which secon is originally executed.

       -V, --version
	      shows the current version of secon

       -h, --help
	      shows the usage information for secon

       -P, --prompt
	      outputs data in a format suitable for a prompt

       -C, --color
	      outputs data with the associated ANSI color codes (requires -P)

       -u, --user
	      show the user of the security context

       -r, --role
	      show the role of the security context

       -t, --type
	      show the type of the security context

       -s, --sensitivity
	      show the sensitivity level of the security context

       -c, --clearance
	      show the clearance level of the security context

       -m, --mls-range
	      show the sensitivity level and clearance, as a range, of the security context

       -R, --raw
	      outputs  the sensitivity level and clearance in an untranslated format.

       -f, --file
	      gets the context from the specified file FILE

       -L, --link
	      gets the context from the specified file FILE (doesn't follow symlinks)

       -p, --pid
	      gets the context from the specified process PID

       --pid-exec
	      gets the exec context from the specified process PID

       --pid-fs
	      gets the fscreate context from the specified process PID

       --current, --self
	      gets the context from the current process

       --current-exec, --self-exec
	      gets the exec context from the current process

       --current-fs, --self-fs
	      gets the fscreate context from the current process

       --parent
	      gets the context from the parent of the current process

       --parent-exec
	      gets the exec context from the parent of the current process

       --parent-fs
	      gets the fscreate context from the parent of the current process

       Additional  argument  CONTEXT may be provided and will be used if no options have been specified to make secon get its context from another
       source.	If that argument is - then the context will be read from stdin.
       If there is no argument, secon will try reading a context from stdin, if that is not a tty, otherwise secon will act as though  --self  had
       been passed.

       If none of --user, --role, --type, --level or --mls-range is passed.  Then all of them will be output.

SEE ALSO

       chcon (1)

AUTHORS

       James Antill (james.antill@redhat.com)

Security Enhanced Linux 					    April 2006								  SECON(1)
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