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$FreeBSD: head/lib/libc/i386/sys/i386_set_watch.3 158268 2006-05-03 17:33:29Z bsd $
.Dd August 24, 2000 .Os .Dt I386_SET_WATCH 3 .Sh NAME .Nm i386_clr_watch , .Nm i386_set_watch .Nd manage i386 debug register values .Sh LIBRARY .Lb libc .Sh SYNOPSIS n machine/reg.h n machine/sysarch.h .Ft int .Fn i386_clr_watch "int watchnum" "struct dbreg *d" .Ft int .Fn i386_set_watch "int watchnum" "unsigned int watchaddr" "int size" "int access" "struct dbreg *d" .Sh DESCRIPTION The .Fn i386_clr_watch function will disable the indicated watch point within the specified debug register set.
p The .Fn i386_set_watch function will set up the specified debug registers as indicated by the arguments. The .Fa watchnum argument specifies which watch register is used, 0, 1, 2, 3, or -1. If .Fa 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 .Fa watchaddr argument specifies the watch address, .Fa size specifies the size in bytes of the area to be watched (1, 2, or 4 bytes), and .Fa access specifies the type of watch point:
p d -literal -offset indent -compact 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. .Ed
p Note that these functions do not actually set or clear breakpoints; they manipulate the indicated debug register set. You must use .Xr ptrace 2 to retrieve and install the debug register values for a process. .Sh RETURN VALUES On success, the .Fn i386_clr_watch function returns 0. On error, -1 returned which indicates that .Fa watchnum is invalid (not in the range of 0-3). If the specified watchnum was already disabled, no error is returned.
p On success, the .Fn i386_set_watch function returns the .Fa watchnum argument, or the watchnum actually used in the case where the specified .Fa watchnum was -1. On error, the .Fn i386_set_watch function returns -1 indicating that the watchpoint could not established because either no more watchpoints are available, or .Fa watchnum , .Fa size , or .Fa access is invalid. .Sh SEE ALSO .Xr ptrace 2 , .Xr procfs 5 .Sh AUTHORS This man page was written by .An Brian S. Dean .