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3 commits

Author SHA1 Message Date
Andrew Bardsley
e5e5b80690 config: Fix to SystemC example's event handling
This patch fixes checkpoint restore in the SystemC hosting example by handling
early PollEvent events correctly before any EventQueue events are posted.

The SystemC event queue handler (SCEventQueue) reports an error if the event
loop is entered with no Events posted.  It is possible for this to happen
after instantiate due to PollEvent events.  This patch separates out
`external' events into a different handler in sc_module.cc to prevent the
error from occurring.

This fix also improves the event handling of asynchronous events by:

    1) Making asynchronous events 'catch up' gem5 time to SystemC
        time to avoid the appearance that events have been lost
        while servicing an asynchronous event that schedules an
        event loop exit event

    2) Add an in_simulate data member to Module to allow the event
        loop to check whether events should be processed or deferred
        until the next time Module::simulate is entered

    3) Cancel pending events around the entry/exit of the event loop
        in Module::simulate

    4) Moving the state initialisation of the example entirely into
        run to correct a problem with early events in checkpoint
        restore.

It is still possible to schedule asynchronous events (and talk PollQueue
actions) while simulate is not running.  This behaviour may stil cause
some problems.
2014-12-02 06:08:09 -05:00
Andrew Bardsley
05bba75cdc config: SystemC Gem5Control top level additions
This patch cleans up a few style issues and adds a few capabilities to the
SystemC top level 'Gem5Control/Gem5System' mechanism.  These include:

    1) A space to store/retrieve a version string for a model
    2) A mechanism for registering functions to be called at the end of
        elaboration to perform simulation setup tasks in SystemC
    3) Adding setGDBRemotePort to the Gem5Control
    4) Changing the sc_set_time_resolution behaviour to instead check that
        the SystemC time resolution is already acceptable
2014-12-02 06:08:06 -05:00
Andrew Bardsley
83f7e7afaf sim: SystemC hosting
This patch hosts gem5 onto SystemC scheduler. There's already an upstream
review board patch that does something similar but this patch ...:

 1) is less obtrusive to the existing gem5 code organisation. It's divided
 into the 'generic' preparatory patches (already submitted) and this patch
 which affects no existing files

 2) does not try to exactly track the gem5 event queue with notifys into
 SystemC and so doesn't requive the event queue to be modified for
 anything other than 'out of event queue' scheduling events

 3) supports debug logging with SC_REPORT

The patch consists of the files:
    util/systemc/
        sc_gem5_control.{cc,hh} -- top level objects to use to
                                   instantiate gem5 Systems within
                                   larger SystemC test harnesses as
                                   sc_module objects
        sc_logger.{cc,hh}       -- logging support
        sc_module.{cc,hh}       -- a separated event loop specific to
                                   SystemC
        stats.{cc,hh}           -- example Stats handling for the sample
                                   top level
        main.{cc,hh}            -- a sample top level

On the downside this patch is only currently functional with C++
configuration at the top level.

The above sc_... files are indended to be compiled alongside gem5 (as a
library, see main.cc for a command line and util/systemc/README for
more details.)

The top-level system instantiation in sc_gem5_control.{cc,hh} provides
two classes: Gem5Control and Gem5System

Gem5Control is a simulation control class (from which a singleton
object should be created) derived from Gem5SystemC::Module which
carries the top level simulation control interface for gem5.  This
includes hosting a system-building configuration file and
instantiating the Root object from that file.

Gem5System is a base class for instantiating renamed gem5 Systems
from the config file hosted by the Gem5Control object.  In use, a
SystemC module class should be made which represents the desired,
instantiable gem5 System.  That class's instances should create
a Gem5System during their construction, set the parameters of that
system and then call instantiate to build that system.  If this
is all carried out in the sc_core::sc_module-derived classes
constructor, the System's external ports will become children of
that module and can then be recovered by name using sc_core::
sc_find_object.

It is intended that this interface is used with dlopen.  To that
end, the header file sc_gem5_control.hh includes no other header
files from gem5 (and so can be easily copied into another project).
The classes Gem5System and Gem5Control have all their member
functions declared `virtual' so that those functions can be called
through the vtable acquired by building the top level Gem5Control
using dlsym(..., "makeGem5Control") and `makeSystem' on the
Gem5Control.
2014-10-16 05:49:54 -04:00