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I386_SET_WATCH(3)     DragonFly Library Functions Manual     I386_SET_WATCH(3)


NAME

     i386_clr_watch, i386_set_watch -- manage i386 debug register values


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <machine/reg.h>
     #include <machine/sysarch.h>

     int
     i386_clr_watch(int watchnum, struct dbreg *d);

     int
     i386_set_watch(int watchnum, unsigned int watchaddr, int size,
	 int access, struct dbreg *d);


DESCRIPTION

     i386_clr_watch() will disable the indicated watch point within the speci-
     fied debug register set.

     i386_set_watch() will set up the specified debug registers as indicated
     by the parameters.  The watchnum argument specifies which watch register
     is used, 0, 1, 2, 3, or -1.  If watchnum is -1, a free watch register is
     found and used.  If there are no free watch registers, an error code of
     -1 is returned.  Watchaddr specifies the watch address, size specifies
     the size in bytes of the area to be watched (1, 2, or 4 bytes), and
     access specifies the type of watch point:

	   DBREG_DR7_EXEC    An execution breakpoint.
	   DBREG_DR7_WRONLY  Break only when the watch area is written to.
	   DBREG_DR7_RDWR    Break when the watch area is read from or written
			     to.

     Note that these functions do not actually set or clear breakpoints; they
     manipulate the indicated debug register set.  You must use ptrace(2) to
     retrieve and install the debug register values for a process.


RETURN VALUES

     i386_clr_watch() returns 0 on success, or -1 if watchnum is invalid (not
     in the range of 0-3).

     i386_set_watch() will return the watchnum argument, or the watchnum actu-
     ally used in the case that watchnum is -1 on success.  On error,
     i386_set_watch() will return -1 indicating that the watchpoint could not
     be set up because either no more watchpoints are available, or watchnum,
     size, or access is invalid.


SEE ALSO

     ptrace(2), procfs(5)


AUTHORS

     This man page was written by Brian S. Dean.

DragonFly 4.3			August 24, 2000 		 DragonFly 4.3

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