non-intrusive tlm-2.0 transaction observation, [-.2em ... · a new pair (initiator, target) of...

I Non-intrusive TLM-2.0 Transaction Observation,Interception, and Augmentation

Philipp A. Hartmann, Maher A. Fakih,

Kim GrüttnerOFFIS Institute for Information TechnologyR&D Division Transportation

September 13th, 2011

24th European SystemC User’s Group MeetingOldenburg, Germany

Philipp A. Hartmann TLM-2.0 Transaction Observation, Augmentation, Interception September 13th, 2011

http://www.offis.de

http://www.offis.de

I 1 Motivation

I Especially in case of immutable third-party TLM-2.0 IP components,wrappers are frequently needed in various scenariosI transaction tracing/recording (already supported by many EDA tools)I protocol and constraint observersI platform integration, non-intrusive feature augmentation

I Building TLM-2.0 wrapper components requires a lot of boiler-plate codeI two additional sockets, including their bindingI forwarding of all TLM-2.0 FW/BW interface calls, even if no functionality is added

I Proposed solution: TLM Observable Sockets

A new pair (initiator, target) of convenience sockets to simplify transaction

forwarding with support for user-defined introspection and manipulation.


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I 2 Outline

1 TLM Observable Sockets

2 Example use cases

3 Limitations & Possible Extensions

4 Conclusion


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I 3 OutlineTLM Observable Sockets


Introduction

Observer infrastructure

Transaction forwarding & management

2 Example use cases


4 Conclusion


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I 4 TLM Observable SocketsIntroduction

I Manual implementation either based onI explicit initiator/target socket pair for

forwarding and internal observationI or single socket (mainly for BW path) and

forwarding/manipulation within wrapper

I Multiple sockets require bookkeeping,

multi-sockets complex to support

I Proposed solution

Wrapper

IP Component

Manual forwarding& Introspection

I Two new convenience socket typesI tlm_utils::tlm_observable_initiator_socket<BUSWIDTH>I tlm_utils::tlm_observable_target_socket<BUSWIDTH>

I Builtin support for base-protocol forwarding (LT/AT)

I Additional utility classes for transaction management, observer infrastructure


http://www.offis.de

http://www.offis.de

I 4 TLM Observable SocketsIntroduction

I Manual implementation either based onI explicit initiator/target socket pair for

forwarding and internal observationI or single socket (mainly for BW path) and

forwarding/manipulation within wrapper

I Multiple sockets require bookkeeping,

multi-sockets complex to support

I Proposed solution

Wrapper

IP ComponentBP

BP

BP

BP

TxnMgmnt

I Two new convenience socket typesI tlm_utils::tlm_observable_initiator_socket<BUSWIDTH>I tlm_utils::tlm_observable_target_socket<BUSWIDTH>

I Builtin support for base-protocol forwarding (LT/AT)

I Additional utility classes for transaction management, observer infrastructure


http://www.offis.de

http://www.offis.de

I 5 Basic class structureTLM Observable Sockets

I Observable sockets are derived

from standard TLM-2.0 sockets

(with configurable bitwidth)

I Transparent support for multi-sockets

→ individual bindings are forwarded,

internal infrastructure built on-demand

I Based on pair of initiator/target socket

pair, as in manual implementation

I GoF observer pattern for introspectionI attach(), detach()I notify()

tlm_target_socket tlm_initiator_socket

tlm_observable_initiator_socket

tlm_observable_target_socket

(template parameters omitted for clarity)


http://www.offis.de

http://www.offis.de

I 5 Basic class structureTLM Observable Sockets

I Observable sockets are derived

from standard TLM-2.0 sockets

(with configurable bitwidth)

I Transparent support for multi-sockets

→ individual bindings are forwarded,

internal infrastructure built on-demand

I Based on pair of initiator/target socket

pair, as in manual implementation

I GoF observer pattern for introspectionI attach(), detach()I notify()

tlm_target_socket tlm_initiator_socket

tlm_observable_initiator_socket

tlm_observable_target_socket

tlm_observable_if

attach()detach()

tlm_observable_socket

initiator_socket()target_socket()observed_socket()

(template parameters omitted for clarity)


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http://www.offis.de

I 6 Observer infrastructure(I)TLM Observable Sockets

I Observers provide a notify callback, invoked by the originating socket

upon a matching notification maskvirtual bool // continue notification/forwarding?notify( tlm_observable_socket& from // source of notification

, tlm_notify_mask m // triggering timing point, tlm_transaction_info & txn ); // extended transaction info

I Notification bitmask tlm_notify_mask enables filtering of

different TLM-2.0 base-protocol timing pointsenum tlm_notify_mask { TLM_NOTIFY_NONE, TLM_NOTIFY_ALL,TLM_NOTIFY_BEGIN, // phase selectorsTLM_NOTIFY_COMPLETED, TLM_NOTIFY_BEGIN_REQ, TLM_NOTIFY_END_REQ,TLM_NOTIFY_AROUND, TLM_NOTIFY_BEGIN_RESP, TLM_NOTIFY_END_RESP,

TLM_NOTIFY_EXTENDED, TLM_NOTIFY_BLOCKING,TLM_NOTIFY_CALL,TLM_NOTIFY_RETURN, TLM_NOTIFY_DMI };


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I 7 Observer infrastructure(II)TLM Observable Sockets

I Observers (inheriting from tlm_transaction_observer) can be

attached and detached during run-timebool attach( tlm_transaction_observer& ); // TLM_NOTIFY_AROUND

virtual bool attach( tlm_notify_mask, tlm_transaction_observer& );

bool detach( tlm_transaction_observer& ); // TLM_NOTIFY_ALLvirtual bool detach( tlm_notify_mask, tlm_transaction_observer& );

I For arbitrary observer types/functions, template versions for

callback (de)registration are providedtypedef bool tlm_notify_callback // callback signature( tlm_observable_socket&, tlm_notify_mask, tlm_transaction_info & );

template< typename T>bool attach( tlm_notify_mask, T&, tlm_notify_callback (T::*cb) );


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I 8 Transaction forwarding & managementTLM Observable Sockets

I Automatic relay of all forward and backward calls along the transaction path

I Observer hooks before and after the relayed call1 store transaction in local pool of active transactions2 prepare notification mask and send notifications to observers3 relay call to destination socket (and update info afterwards)

4 iff transaction is intercepted by an observer,skip remaining notifications and relay

5 send notifications to observers in reverse order6 cleanup transaction info, iff transaction has completed

I tlm_transaction_info holds (local) information aboutI source and/or destination socketI payload, phase, and delay (can be updated)I automatically managed and pooled


http://www.offis.de

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I 8 Transaction forwarding & managementTLM Observable Sockets

I Automatic relay of all forward and backward calls along the transaction path

I Observer hooks before and after the relayed call1 store transaction in local pool of active transactions2 prepare notification mask and send notifications to observers3 relay call to destination socket (and update info afterwards)4 iff transaction is intercepted by an observer,

skip remaining notifications and relay5 send notifications to observers in reverse order6 cleanup transaction info, iff transaction has completed

I tlm_transaction_info holds (local) information aboutI source and/or destination socketI payload, phase, and delay (can be updated)I automatically managed and pooled


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I 9 OutlineExample use cases


2 Example use cases

Direct-Memory Access & Endianness

Timing observation

Power management: power/clock gating


4 Conclusion


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I 10 Disabling Direct-Memory AccessExample use cases

I Cancel all DMI requests on am observed target socketvirtual boolnotify( tlm_observable_socket&, tlm_notify_mask m, tlm_transaction_info & txn ) {

if( m & TLM_NOTIFY_DMI ) { // within get_direct_mem_ptrtlm_dmi& dmi = *txn.dmi();dmi.set_start_address(0); dmi.set_end_address(~0ULL);return false; // abort request

}txn.payload().set_dmi_allowed( false ); // within a transport callreturn true; // continue transaction

}

I Since this is a frequent requirement, especially when augmenting a component’s

behaviour, this is already supported by tlm_observable_socket

void inhibit_dmi( bool yesno ); // default − false

I When activated, builtin functionality invalidates DMI pointers as well


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I 11 Adding Endianness ConversionExample use cases

I Assuming an initiator with internal endianness different from the host’s

endianness, but without support for endianness conversion

I Adding (word-only) endianness conversion1 byvirtual boolnotify( tlm_observable_socket& s, tlm_notify_mask m, tlm_transaction_info & txn ) {

if( m & TLM_NOTIFY_BEGIN ) { // start of transactiontlm_to_hostendian_generic<unsigned> ( txn.payload(), s.buswidth() );

} else { // end of transactiontlm_from_hostendian_generic<unsigned>( txn.payload(), s.buswidth() );

}return true; // continue transaction

}

I Attach observer with default notification mask

TLM_NOTIFY_AROUND == TLM_NOTIFY_BEGIN | TLM_NOTIFY_COMPLETED

1shorter datatypes not covered here!


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I 12 Timing observationExample use cases

I A multi-core architecture for real-time applications needs to provide a predictable

on-chip interconnect infrastructure with guaranteed maximum latencies

I A simple arbitration delay observer can be attached to an AT interconnectinitiator.attach( TLM_NOTIFY_BEGIN_REQ, *this );

I Checking the forwarded transaction on the outgoing initiator socket is sufficient,

due to the automatic local transaction managementvirtual boolnotify( tlm_observable_socket&, tlm_notify_mask, tlm_transaction_info & txn ) {

if( txn.last_update() > max_arbitration_delay )SC_REPORT_ERROR( ... );

return true;}


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I 13 Power management: power/clock gatingExample use cases

I Externally adding support for clock/power gating to a component requires correct

use (rather non-use) of switched-off parts

I Different approaches possible, depending on the applicationvirtual boolnotify( /∗ ... ∗/ ) {

if( is_disabled( txn.start() ) ) { // component is still disabledif( wakeup_time() == sc_max_time() ) {

// report an errortxn.set_response_status( TLM_COMMAND_ERROR_RESPONSE );txn.complete();return false;

}// add delay to transactiontxn.delay( wakeup_time()-txn.start() );

}return true;

}


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I 14 OutlineLimitations & Possible Extensions


2 Example use cases


Hierarchical binding

Support for custom protocols

4 Conclusion


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I 15 Limitations & Possible Extensions

I Hierarchical binding of multi-sockets not yet supportedI multi-sockets use dedicated overloads for hierarchical bindI transparent socket binding is not explicitly multi-socket awareI required overloads could be added for TLM-2.0 convenience multi-sockets

(multi_passthrough_target/initiator_socket)I user-defined sockets based on a similar technique still a problem

I Support for custom phases and protocol types possible?I current approach limited to tlm_generic_payload and TLM-2.0 base-protocolI limited support for extended phases (TLM_NOTIFY_EXTENDED)I forwarding and management code largely independent of protocolI refactoring of the different parts of the implementation→ using policy-based design to separate concerns


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I 16 OutlineConclusion


2 Example use cases


4 Conclusion


http://www.offis.de

http://www.offis.de

I 17 Conclusion

I New convenience sockets for TLM-2.0 transactionobservation, interception and augmentationI support for tlm_generic_payload and TLM-2.0 base-protocolI automatic/transparent base-protocol implementation,

transaction forwarding, and memory management

I Observation infrastructure, based on LT/AT base-protocol timing pointsI attaching/detaching observers during simulationI modification of payload and timing supported

I Open-source proof-of-concept implementation soon

to be available at http://complex.offis.de

I Submission to OSCI TLM Working Group intended later this year,once IEEE 1666-2011 is releasedI Feedback and discussion welcome!


http://www.offis.de

http://complex.offis.de

http://www.offis.de

I 18

Thanks for your attention!

Questions?


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