target_resume() doxygen

Add doxygen for target_resume() ... referencing the still-unresolved
confusion about what the "debug_execution" parameter means (not all
CPU support code acts the same).

The 'handle_breakpoints" param seems to have resolved the main issue
with its semantics, but it wasn't part of the function spec before.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

diff --git a/src/target/target.c b/src/target/target.c
index 2522408382e31e695c7af9f76da6278cb950ceac..9596302d7db41cbd5829f1e93444e0ef59bdd6f4 100644 (file)
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -424,6 +424,36 @@ int target_halt(struct target *target)
        return ERROR_OK;
 }
 
+/**
+ * Make the target (re)start executing using its saved execution
+ * context (possibly with some modifications).
+ *
+ * @param target Which target should start executing.
+ * @param current True to use the target's saved program counter instead
+ *     of the address parameter
+ * @param address Optionally used as the program counter.
+ * @param handle_breakpoints True iff breakpoints at the resumption PC
+ *     should be skipped.  (For example, maybe execution was stopped by
+ *     such a breakpoint, in which case it would be counterprodutive to
+ *     let it re-trigger.
+ * @param debug_execution False if all working areas allocated by OpenOCD
+ *     should be released and/or restored to their original contents.
+ *     (This would for example be true to run some downloaded "helper"
+ *     algorithm code, which resides in one such working buffer and uses
+ *     another for data storage.)
+ *
+ * @todo Resolve the ambiguity about what the "debug_execution" flag
+ * signifies.  For example, Target implementations don't agree on how
+ * it relates to invalidation of the register cache, or to whether
+ * breakpoints and watchpoints should be enabled.  (It would seem wrong
+ * to enable breakpoints when running downloaded "helper" algorithms
+ * (debug_execution true), since the breakpoints would be set to match
+ * target firmware being debugged, not the helper algorithm.... and
+ * enabling them could cause such helpers to malfunction (for example,
+ * by overwriting data with a breakpoint instruction.  On the other
+ * hand the infrastructure for running such helpers might use this
+ * procedure but rely on hardware breakpoint to detect termination.)
+ */
 int target_resume(struct target *target, int current, uint32_t address, int handle_breakpoints, int debug_execution)
 {
        int retval;
@@ -435,9 +465,9 @@ int target_resume(struct target *target, int current, uint32_t address, int hand
                return ERROR_FAIL;
        }
 
-       /* note that resume *must* be asynchronous. The CPU can halt before we poll. The CPU can
-        * even halt at the current PC as a result of a software breakpoint being inserted by (a bug?)
-        * the application.
+       /* note that resume *must* be asynchronous. The CPU can halt before
+        * we poll. The CPU can even halt at the current PC as a result of
+        * a software breakpoint being inserted by (a bug?) the application.
         */
        if ((retval = target->type->resume(target, current, address, handle_breakpoints, debug_execution)) != ERROR_OK)
                return retval;