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I386_SET_WATCH(3) BSD 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

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.

BSD August 24, 2000 BSD

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