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i386_clr_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

     The i386_clr_watch() function will disable the indicated watch point
     within the specified debug register set.

     The i386_set_watch() function will set up the specified debug registers
     as indicated by the arguments.  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.  The watchaddr argument 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

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

     The i386_set_watch() function will return the watchnum argument, or the
     watchnum actually 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.

FreeBSD 5.4			August 24, 2000 		   FreeBSD 5.4

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