Re: [patch] gdbserver: Add support for Z0/Z1 packets

Pedro Alves
2009-06-20T22:01:15Z

On Friday 19 June 2009 14:55:56, Aleksandar Ristovski wrote:

> RCS file: /cvs/src/src/gdb/gdbserver/target.h,v
> retrieving revision 1.36
> diff -u -p -r1.36 target.h
> --- target.h    1 Apr 2009 22:50:24 -0000       1.36
> +++ target.h    19 Jun 2009 13:47:44 -0000
> @@ -213,6 +213,14 @@ struct target_ops
>    int (*read_auxv) (CORE_ADDR offset, unsigned char *myaddr,
>                     unsigned int len);
>
> +  /* Insert and remove breakpoint.  Argument TYPE can be:
> +       '0' = software-breakpoint
> +       '1' = hardware-breakpoint

^ spurious space

> +     Returns 0 if successful, 1 otherwise.  */
> +
> +  int (*insert_breakpoint) (char type, CORE_ADDR addr);
> +  int (*remove_breakpoint) (char type, CORE_ADDR addr);

Z0 and Z1 breakpoints also take a 'len' argument, just
like Z2-Z4. You should also pass those down.

But, Let's take a step back --- why not just rename the
insert_watchpoint|remove_watchpoint functions to insert_point,remove_point,
and relax the type checks in server.c:

if (the_target->insert_watchpoint == NULL
|| (type < '2' || type > '4'))
{

... to also allow type == '0' or '1' ?

Looking at your nto-low.c file in the original patch, you were
doing this:

+static int
+nto_insert_breakpoint (char type, CORE_ADDR addr)
^^^^^^^^^^
+{
+ TRACE ("%s\n", __func__);
+
+ return nto_insert_watchpoint (type, addr, 1);
^^^^^^^^^^
+}

In the latest patch, you're doing this:

+static int
+nto_insert_breakpoint (char type, CORE_ADDR addr)
+{
+ TRACE ("%s\n", __func__);
+ switch (type)
+ {
+ case '0': /* software-breakpoint */
+ return nto_breakpoint (addr, _DEBUG_BREAK_EXEC, 0);
+ case '1': /* hardware-breakpoint */
+ return nto_breakpoint (addr, _DEBUG_BREAK_EXEC | _DEBUG_BREAK_HW, 0);
+ }
+ return 1; /* Not supported. */
+}

+static int
+nto_insert_watchpoint (char type, CORE_ADDR addr, int len)
+{
+ int wtype = _DEBUG_BREAK_HW; /* Always request HW. */
+
+ TRACE ("%s type:%c\n", __func__, type);
+ switch (type)
+ {
+ case '2': /* write watchpoint */
+ wtype |= _DEBUG_BREAK_RW;
+ break;
+ case '3': /* read watchpoint */
+ wtype |= _DEBUG_BREAK_RD
+ break;
+ case '4': /* access watchpoint */
+ wtype |= _DEBUG_BREAK_RW;
+ break;
+ default:
+ return 1; /* Not supported. */
+ }
+ return nto_breakpoint (addr, wtype, 0);
+}

That is, still always deferring to a single function
(nto_breakpoint).

This suggests that the insert_breakpoint and insert_watchpoint
interface distintion is unnecessary.

--
Pedro Alves