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I386_SET_WATCH(3)      FreeBSD 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
     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
     On success, the i386_clr_watch() function returns 0.  On error, -1
     returned which indicates that watchnum is invalid (not in the range of
     0-3).  If the specified watchnum was already disabled, no error is
     returned.

     On success, the i386_set_watch() function returns the watchnum argument,
     or the watchnum actually used in the case where the specified watchnum
     was -1.  On error, the i386_set_watch() function returns -1 indicating
     that the watchpoint could not established 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 11.0-PRERELEASE         August 24, 2000        FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | AUTHORS

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