Hello.
On Sat, 11 Feb 2012, Eric Decker wrote:
I have problem with Resource.request() in SoftwareInit.init(), simple code
(the same code as in RF230DriverLayerP.SoftwareInit.init()):
You can't do this in SoftwareInit.init.
Why? Because FcfsResource gets initialized via SoftwareInit.init and order of
initialization is not stated nor can you count on it.
SoftwareInit does not guarantee any ordering.
----> You can't call Resource.request for a Resource that uses Fcfs are the
queuing mechanism.
Do it from Boot.booted.
I read about this issue in "TOS programming book" in chapter "4.4.
Multiple wirings". (The order of the calls is not defined.)
There are following issues:
1) The standard tinyos code uses this wrong mechanism. For example (at least):
./platforms/mulle/fix/RF230DriverHwAckP.nc
./platforms/mulle/fix/RF230DriverLayerP.nc
./chips/rf230/RF230DriverLayerP.nc
./chips/rf230/RF230DriverHwAckP.nc
./chips/rf212/RF212DriverLayerP.nc
2) How to implement "LocalIeeeEui64C" on external shared bus that must be
available before the Boot.booted() event (TEP122).
How to establish "specific initialization ordering" for
MainC.SoftwareInit (tep107) ?
What are you referring to in TEP107. 107 doesn't say anything about specific
ordering.
Yes, TEP107.
Yes, TEP107 does not say anything _how_ to implement ordering.
But there is statement:
... "Components whose initialization does not directly depend on hardware
resources SHOULD wire to MainC.SoftwareInit. If a component requires a
specific initialization ordering, then it is responsible for establishing
that ordering. Due to the semantics of Init, this is usually quite rare; a
component SHOULD NOT introduce initialization dependencies unless they are
required." ....
Is there some mechanism to establish call order ?
I see two solution.
1) Add next initialization layer between PlatformInit and SoftwareInit.
2) Rebind "component's data initialization"/"software data init" from
SoftwareInit.init() to PlatformInit.init(). (and modify TEP107)
For example:
===================================================================
--- tos/system/SimpleFcfsArbiterC.nc (revision 5889)
+++ tos/system/SimpleFcfsArbiterC.nc (working copy)
@@ -89,11 +89,11 @@
uses interface ResourceConfigure[uint8_t id];
}
implementation {
- components MainC;
+ components RealMainP;
components new FcfsResourceQueueC(uniqueCount(resourceName)) as Queue;
components new SimpleArbiterP() as Arbiter;
- MainC.SoftwareInit -> Queue;
+ RealMainP.PlatformInit -> Queue;
Resource = Arbiter;
ResourceRequested = Arbiter;
===================================================================
--- tos/system/FcfsArbiterC.nc (revision 5889)
+++ tos/system/FcfsArbiterC.nc (working copy)
@@ -96,11 +96,11 @@
uses interface ResourceConfigure[uint8_t id];
}
implementation {
- components MainC;
+ components RealMainP;
components new FcfsResourceQueueC(uniqueCount(resourceName)) as Queue;
components new ArbiterP(uniqueCount(resourceName)) as Arbiter;
- MainC.SoftwareInit -> Queue;
+ RealMainP.PlatformInit -> Queue;
Resource = Arbiter;
ResourceRequested = Arbiter;
===================================================================
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