target: Rebuilt the non-halting I/O heuristic, replacing it with a ta…

…rget option

src/target/target.c

@@ -334,13 +334,10 @@ bool target_mem64_write(target_s *const target, const target_addr64_t dest, cons
 	return target_check_error(target);
 }
 
-/* target_mem_access_needs_halt() is true if the target needs to be halted during jtag memory access */
-
+/* Returns true if the target needs halting to access memory on it */
 bool target_mem_access_needs_halt(target_s *target)
 {
-	/* assume all arm processors allow memory access while running, and no riscv does. */
-	bool is_riscv = target && target->core && strstr(target->core, "RVDBG");
-	return is_riscv;
+	return !(target->target_options & TOPT_NON_HALTING_MEM_IO);
 }
 
 /* Register access functions */

src/target/target_internal.h

@@ -27,8 +27,9 @@
 #include "platform_support.h"
 #include "target_probe.h"
 
-#define TOPT_INHIBIT_NRST           (1U << 0U)
-#define TOPT_IN_SEMIHOSTING_SYSCALL (1U << 31U)
+#define TOPT_INHIBIT_NRST           (1U << 0U)  /* Target misbehaves if reset using nRST line */
+#define TOPT_NON_HALTING_MEM_IO     (1U << 30U) /* Target does not need halting for memory I/O */
+#define TOPT_IN_SEMIHOSTING_SYSCALL (1U << 31U) /* Target is currently in a semihosting syscall */
 
 extern target_s *target_list;