This patch adds a config script that broadly replicates the behaviour
of lat_mem_rd. The test is based on traffic generators, and as such we
simply randomise addresses in increasingly large ranges, and play them
back using the trace functionality of the traffic generator.
The test script is accompanied by a post-processing and visualisation
script. At the moment no configurability is added to tweak the memory
hierarchy, but a follow on patch could easily extend the
functionality.
This patch introduces the ability of making the coherent crossbar the
point of coherency. If so, the crossbar does not forward packets where
a cache with ownership has already committed to responding, and also
does not forward any coherency-related packets that are not intended
for a downstream memory controller. Thus, invalidations and upgrades
are turned around in the crossbar, and the memory controller only sees
normal reads and writes.
In addition this patch moves the express snoop promotion of a packet
to the crossbar, thus allowing the downstream cache to check the
express snoop flag (as it should) for bypassing any blocking, rather
than relying on whether a cache is responding or not.
This patch changes how the cache determines if snoops should be
forwarded from the memory side to the CPU side. Instead of having a
parameter, the cache now looks at the port connected on the CPU side,
and if it is a snooping port, then snoops are forwarded. Less error
prone, and less parameters to worry about.
The patch also tidies up the CPU classes to ensure that their I-side
port is not snooping by removing overrides to the snoop request
handler, such that snoop requests will panic via the default
MasterPort implement
Add a platform with support for both aarch32 and aarch64. This
platform implements a subset of the devices in a real Versatile
Express and extends it with some gem5-specific functionality. It is in
many ways similar to the old VExpress_EMM64 platform, but supports the
following new features:
* Automatic PCI interrupt assignment
* PCI interrupts allocated in a contiguous range.
* Automatic boot loader selection (32-bit / 64-bit)
* Cleaner memory map where gem5-specific devices live in CS5 which
isn't used by current Versatile Express platforms.
* No fake devices. Devices that were previously faked will be
removed from the device tree instead.
* Support for 510 GiB contiguous memory
This patch allows the ruby random tester to use ruby ports that may only
support instr or data requests. This patch is similar to a previous changeset
(8932:1b2c17565ac8) that was unfortunately broken by subsequent changesets.
This current patch implements the support in a more straight-forward way.
Since retries are now tested when running the ruby random tester, this patch
splits up the retry and drain check behavior so that RubyPort children, such
as the GPUCoalescer, can perform those operations correctly without having to
duplicate code. Finally, the patch also includes better DPRINTFs for
debugging the tester.
This patch adds changes to the configuration scripts to support elastic
tracing and replay.
The patch adds a command line option to enable elastic tracing in SE mode
and FS mode. When enabled the Elastic Trace cpu probe is attached to O3CPU
and a few O3 CPU parameters are tuned. The Elastic Trace probe writes out
both instruction fetch and data dependency traces. The patch also enables
configuring the TraceCPU to replay traces using the SE and FS script.
The replay run is designed to resume from checkpoint using atomic cpu to
restore state keeping it consistent with FS run flow. It then switches to
TraceCPU to replay the input traces.
The gem5's current PCI host functionality is very ad hoc. The current
implementations require PCI devices to be hooked up to the
configuration space via a separate configuration port. Devices query
the platform to get their config-space address range. Un-mapped parts
of the config space are intercepted using the XBar's default port
mechanism and a magic catch-all device (PciConfigAll).
This changeset redesigns the PCI host functionality to improve code
reuse and make config-space and interrupt mapping more
transparent. Existing platform code has been updated to use the new
PCI host and configured to stay backwards compatible (i.e., no
guest-side visible changes). The current implementation does not
expose any new functionality, but it can easily be extended with
features such as automatic interrupt mapping.
PCI devices now register themselves with a PCI host controller. The
host controller interface is defined in the abstract base class
PciHost. Registration is done by PciHost::registerDevice() which takes
the device, its bus position (bus/dev/func tuple), and its interrupt
pin (INTA-INTC) as a parameter. The registration interface returns a
PciHost::DeviceInterface that the PCI device can use to query memory
mappings and signal interrupts.
The host device manages the entire PCI configuration space. Accesses
to devices decoded into the devices bus position and then forwarded to
the correct device.
Basic PCI host functionality is implemented in the GenericPciHost base
class. Most platforms can use this class as a basic PCI controller. It
provides the following functionality:
* Configurable configuration space decoding. The number of bits
dedicated to a device is a prameter, making it possible to support
both CAM, ECAM, and legacy mappings.
* Basic interrupt mapping using the interruptLine value from a
device's configuration space. This behavior is the same as in the
old implementation. More advanced controllers can override the
interrupt mapping method to dynamically assign host interrupts to
PCI devices.
* Simple (base + addr) remapping from the PCI bus's address space to
physical addresses for PIO, memory, and DMA.
Add support for automatically discover available platforms. The
Python-side uses functionality similar to what we use when
auto-detecting available CPU models. The machine IDs have been updated
to match the platform configurations. If there isn't a matching
machine ID, the configuration scripts default to -1 which Linux uses
for device tree only platforms.
Added the missing types EthernetAddr and Current to the JSON/INI file
reader example configs/example/read_config.py.
Also added __str__ to EthernetAddr to make values appear in the same form
in JSON an INI files.
This patch adds yet another twist to the memtest cache hierarchy, in that
the writeback_clean option is toggled at every level to match the
clusivity of the downstream cache.
This patch adds the necessary commands and cache functionality to
allow clean writebacks. This functionality is crucial, especially when
having exclusive (victim) caches. For example, if read-only L1
instruction caches are not sending clean writebacks, there will never
be any spills from the L1 to the L2. At the moment the cache model
defaults to not sending clean writebacks, and this should possibly be
re-evaluated.
The implementation of clean writebacks relies on a new packet command
WritebackClean, which acts much like a Writeback (renamed
WritebackDirty), and also much like a CleanEvict. On eviction of a
clean block the cache either sends a clean evict, or a clean
writeback, and if any copies are still cached upstream the clean
evict/writeback is dropped. Similarly, if a clean evict/writeback
reaches a cache where there are outstanding MSHRs for the block, the
packet is dropped. In the typical case though, the clean writeback
allocates a block in the downstream cache, and marks it writable if
the evicted block was writable.
The patch changes the O3_ARM_v7a L1 cache configuration and the
default L1 caches in config/common/Caches.py
This patch adds an new twist to the memtest cache hierarchy, in that
it switches from mostly inclusive to mostly exclusive at every level
in the tree. This has helped weed out plenty issues, and serves as a
good stress tests.
This patch adds a parameter to control the cache clusivity, that is if
the cache is mostly inclusive or exclusive. At the moment there is no
intention to support strict policies, and thus the options are: 1)
mostly inclusive, or 2) mostly exclusive.
The choice of policy guides the behaviuor on a cache fill, and a new
helper function, allocOnFill, is created to encapsulate the decision
making process. For the timing mode, the decision is annotated on the
MSHR on sending out the downstream packet, and in atomic we directly
pass the decision to handleFill. We (ab)use the tempBlock in cases
where we are not allocating on fill, leaving the rest of the cache
unaffected. Simple and effective.
This patch also makes it more explicit that multiple caches are
allowed to consider a block writable (this is the case
also before this patch). That is, for a mostly inclusive cache,
multiple caches upstream may also consider the block exclusive. The
caches considering the block writable/exclusive all appear along the
same path to memory, and from a coherency protocol point of view it
works due to the fact that we always snoop upwards in zero time before
querying any downstream cache.
Note that this patch does not introduce clean writebacks. Thus, for
clean lines we are essentially removing a cache level if it is made
mostly exclusive. For example, lines from the read-only L1 instruction
cache or table-walker cache are always clean, and simply get dropped
rather than being passed to the L2. If the L2 is mostly exclusive and
does not allocate on fill it will thus never hold the line. A follow
on patch adds the clean writebacks.
The patch changes the L2 of the O3_ARM_v7a CPU configuration to be
mostly exclusive (and stats are affected accordingly).
This patch enables modeling a complete Hybrid Memory Cube (HMC) device. It
highly reuses the existing components in gem5's general memory system with some
small modifications. This changeset requires additional patches to model a
complete HMC device.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
makeSparcSystem() in configs/common/FSConfig.py is missing the cmdLine
parameter Without the parameter the simulation fails to start. With the
parameter the simulation starts properly.
Adds SMT support to the "simple" CPU models so that they can be
used with other SMT-supported CPUs. Example usage: this enables
the TimingSimpleCPU to be used to warmup caches before swapping to
detailed mode with the in-order or out-of-order based CPU models.
Added a new directory in configs (learning_gem5) to hold the scripts that are
used in the book. See http://lowepower.com/jason/learning_gem5/ for a working
copy. For now, only the scripts in Part 1: Getting started with gem5
have been added. A separate patch adds tests for these scripts.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
We no longer use the C library based random number generator: random().
Instead we use the C++ library provided rng. So setting the random seed for
the RubySystem class has no effect. Hence the variable and the corresponding
option are being dropped.
Open up for other subclasses to BaseCache and transition to using the
explicit Cache subclass.
--HG--
rename : src/mem/cache/BaseCache.py => src/mem/cache/Cache.py
This patch serves to avoid name clashes with the classic cache. For
some reason having two 'SimObject' files with the same name creates
problems.
--HG--
rename : src/mem/ruby/structures/Cache.py => src/mem/ruby/structures/RubyCache.py
We no longer use the C library based random number generator: random().
Instead we use the C++ library provided rng. So setting the random seed for
the RubySystem class has no effect. Hence the variable and the corresponding
option are being dropped.
Expose MessageBuffers from SLICC controllers as SimObjects that can be
manipulated in Python. This patch has numerous benefits:
1) First and foremost, it exposes MessageBuffers as SimObjects that can be
manipulated in Python code. This allows parameters to be set and checked in
Python code to avoid obfuscating parameters within protocol files. Further, now
as SimObjects, MessageBuffer parameters are printed to config output files as a
way to track parameters across simulations (e.g. buffer sizes)
2) Cleans up special-case code for responseFromMemory buffers, and aligns their
instantiation and use with mandatoryQueue buffers. These two special buffers
are the only MessageBuffers that are exposed to components outside of SLICC
controllers, and they're both slave ends of these buffers. They should be
exposed outside of SLICC in the same way, and this patch does it.
3) Distinguishes buffer-specific parameters from buffer-to-network parameters.
Specifically, buffer size, randomization, ordering, recycle latency, and ports
are all specific to a MessageBuffer, while the virtual network ID and type are
intrinsics of how the buffer is connected to network ports. The former are
specified in the Python object, while the latter are specified in the
controller *.sm files. Unlike buffer-specific parameters, which may need to
change depending on the simulated system structure, buffer-to-network
parameters can be specified statically for most or all different simulated
systems.
The RubyCache (CacheMemory) latency parameter is only used for top-level caches
instantiated for Ruby coherence protocols. However, the top-level cache hit
latency is assessed by the Sequencer as accesses flow through to the cache
hierarchy. Further, protocol state machines should be enforcing these cache hit
latencies, but RubyCaches do not expose their latency to any existng state
machines through the SLICC/C++ interface. Thus, the RubyCache latency parameter
is superfluous for all caches. This is confusing for users.
As a step toward pushing L0/L1 cache hit latency into the top-level cache
controllers, move their latencies out of the RubyCache declarations and over to
their Sequencers. Eventually, these Sequencer parameters should be exposed as
parameters to the top-level cache controllers, which should assess the latency.
NOTE: Assessing these latencies in the cache controllers will require modifying
each to eliminate instantaneous Ruby hit callbacks in transitions that finish
accesses, which is likely a large undertaking.
Transaction Level Modeling (TLM2.0) is widely used in industry for creating
virtual platforms (IEEE 1666 SystemC). This patch contains a standard compliant
implementation of an external gem5 port, that enables the usage of gem5 as a
TLM initiator component in SystemC based virtual platforms. Both TLM coding
paradigms loosely timed (b_transport) and aproximately timed (nb_transport) are
supported.
Compared to the original patch a TLM memory manager was added. Furthermore, the
transaction object was removed and for each TLM payload a PacketPointer that
points to the original gem5 packet is added as an TLM extension. For event
handling single events are now created.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch takes the final step in removing the is_top_level parameter
from the cache. With the recent changes to read requests and write
invalidations, the parameter is no longer needed, and consequently
removed.
This also means that asymmetric cache hierarchies are now fully
supported (and we are actually using them already with L1 caches, but
no table-walker caches, connected to a shared L2).
This patch adds a parameter to the BaseCache to enable a read-only
cache, for example for the instruction cache, or table-walker cache
(not for x86). A number of checks are put in place in the code to
ensure a read-only cache does not end up with dirty data.
A follow-on patch adds suitable read requests to allow a read-only
cache to explicitly ask for clean data.
This changeset adds support for aarch64 in kvm. The CPU module
supports both checkpointing and online CPU model switching as long as
no devices are simulated by the host kernel. It currently has the
following limitations:
* The system register based generic timer can only be simulated by
the host kernel. Workaround: Use a memory mapped timer instead to
simulate the timer in gem5.
* Simulating devices (e.g., the generic timer) in the host kernel
requires that the host kernel also simulates the GIC.
* ID registers in the host and in gem5 must match for switching
between simulated CPUs and KVM. This is particularly important
for ID registers describing memory system capabilities (e.g.,
ASID size, physical address size).
* Switching between a virtualized CPU and a simulated CPU is
currently not supported if in-kernel device emulation is
used. This could be worked around by adding support for switching
to the gem5 (e.g., the KvmGic) side of the device models. A
simpler workaround is to avoid in-kernel device models
altogether.
This patch simplifies the overall CPU by changing the TLB caches such
that they do not forward snoops to the table walker port(s). Note that
only ARM and X86 are affected.
There is no reason for the ports to snoop as they do not actually take
any action, and from a performance point of view we are better of not
snooping more than we have to.
Should it at a later point be required to snoop for a particular TLB
design it is easy enough to add it back.
Currently, each op class has a parameter issueLat that denotes the cycles after
which another op of the same class can be issued. As of now, this latency can
either be one cycle (fully pipelined) or same as execution latency of the op
(not at all pipelined). The fact that issueLat is a parameter of type Cycles
makes one believe that it can be set to any value. To avoid the confusion, the
parameter is being renamed as 'pipelined' with type boolean. If set to true,
the op would execute in a fully pipelined fashion. Otherwise, it would execute
in an unpipelined fashion.
This patch ensures that the CPU progress Event is triggered for the new set of
switched_cpus that get scheduled (e.g. during fast-forwarding). it also avoids
printing the interval state if the cpu is currently switched out.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch adds an example configuration in ext/sst/tests/ that allows
an SST/gem5 instance to simulate a 4-core AArch64 system with SST's
memHierarchy components providing all the caches and memories.
When using gem5 as a slave simulator, it will not advance the
clock on its own and depends on the master simulator calling
simulate(). This new option lets us use the Python scripts
to do all the configuration while stopping short of actually
simulating anything.
This patch adds a random option to memtest.py which allows the user to
easily test valid random tree topologies. The patch also adds a
wrapper script to run soak tests using the newly introduced option.
We also adjust the progress interval and progress limit check to make
the output less noisy, and avoid false positives.
Bring on the pain.
This patch enables users to speficy --os-type on the command
line. This option is used to take specific actions for an OS type,
such as changing the kernel command line. This patch is part of the
Android KitKat enablement.
This patch modifies FSConfig.py to look for 'android' only in disk
image name. Before this patch, 'android' was searched in full
disk path.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch introduces a few subclasses to the CoherentXBar and
NoncoherentXBar to distinguish the different uses in the system. We
use the crossbar in a wide range of places: interfacing cores to the
L2, as a system interconnect, connecting I/O and peripherals,
etc. Needless to say, these crossbars have very different performance,
and the clock frequency alone is not enough to distinguish these
scenarios.
Instead of trying to capture every possible case, this patch
introduces dedicated subclasses for the three primary use-cases:
L2XBar, SystemXBar and IOXbar. More can be added if needed, and the
defaults can be overridden.
Previously, the user would have to manually set access_backing_store=True
on all RubyPorts (Sequencers) in the config files.
Now, instead there is one global option that each RubyPort checks on
initialization.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This is a rather unfortunate copy of the memtest.py example script,
that actually stresses the system with true sharing as opposed to the
false sharing of the MemTest. To do so it uses TrafficGen instances to
generate the reads/writes, and MemCheckerMonitor combined with the
MemChecker to check the validity of the read/written values.
As a bonus, this script also enables the addition of prefetchers, and
the traffic is created to have a mix of random addresses and linear
strides. We use the TaggedPrefetcher since the packets do not have a
request with a PC.
At the moment the code is almost identical to the memtest.py script,
and no effort has been made to factor out the construction of the
tree. The challenge is that the instantiation and connection of the
testers and monitors is done as part of the tree building.
This patch revamps the memtest example script and allows for the
insertion of testers at any level in the cache hierarchy. Previously
all created topologies placed testers only at the very top, and the
tree was thus entirely symmetric. With the changes made, it is possible
to not only place testers at the leaf caches (L1), but also to connect
testers at the L2, L3 etc.
As part of the changes the object hierarchy is also simplified to
ensure that the visual representation from the DOT printing looks
sensible. Using SubSystems to group the objects is one of the key
features.
The MemTest class really only tests false sharing, and as such there
was a lot of old cruft that could be removed. This patch cleans up the
tester, and also makes it more clear what the assumptions are. As part
of this simplification the reference functional memory is also
removed.
The regression configs using MemTest are updated to reflect the
changes, and the stats will be bumped in a separate patch. The example
config will be updated in a separate patch due to more extensive
re-work.
In a follow-on patch a new tester will be introduced that uses the
MemChecker to implement true sharing.
Although you can put a list of colon-separated directory names
in M5_PATH, the current code just takes the first one that
exists and assumes all files must live there. This change
makes the code search the specified list of directories
for each individual binary or disk image that's requested.
The main motivation is that the x86/Alpha binaries and the
ARM binaries are in separate downloads, and thus naturally
end up in separate directories. With this change, you can
have M5_PATH point to those two directories, then run any
FS regression test without changing M5_PATH. Currently,
you either have to merge the two download directories
or change M5_PATH (or do something else I haven't figured out).
This patch uses the recently added XOR hashing capabilities for the
DRAM channel interleaving. This avoids channel biasing due to strided
access patterns.
This patch changes the DRAM channel interleaving default behaviour to
be more representative. The default address mapping (RoRaBaCoCh) moves
the channel bits towards the least significant bits, and uses 128 byte
as the default channel interleaving granularity.
These defaults can be overridden if desired, but should serve as a
sensible starting point for most use-cases.
Fix the makeArmSystem routine to reflect recent changes that support kernel
commandline option when running android. Without this fix, trying to run
android encounters a 'reference before assignment' error.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
DMA Controller was not being connected to the network for the MESI_Three_Level
protocol as was being done in the other protocol config files. Without this
patch, this protocol segfaults during startup.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
when trying to dual boot on arm build_drive_system will only use the default
values for the dtb file, number of processors, and disk image. if you are using
the non-default files by passing values on the command line for example, or by
making a new entry in Benchmarks.py, the build config scripts will still look
for the default files. this will lead to the wrong system files being used, or
the simulator will fail if you do not have them.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
This patch gives the user direct influence over the number of DRAM
ranks to make it easier to tune the memory density without affecting
the bandwidth (previously the only means of scaling the device count
was through the number of channels).
The patch also adds some basic sanity checks to ensure that the number
of ranks is a power of two (since we rely on bit slices in the address
decoding).
This patch adds the --memchecker option, to denote that a MemChecker
should be instantiated for the system. The exact usage of the MemChecker
depends on the system configuration.
For now CacheConfig.py makes use of the option, adding MemCheckerMonitor
instances between CPUs and D-Caches.
Note, however, that currently this only provides limited checking on a
running system; other parts of the system, such as I/O devices are not
monitored, and may cause warnings to be issued by the monitor.
More documentation at http://gem5.org/Simpoints
Steps to profile, generate, and use SimPoints with gem5:
1. To profile workload and generate SimPoint BBV file, use the
following option:
--simpoint-profile --simpoint-interval <interval length>
Requires single Atomic CPU and fastmem.
<interval length> is in number of instructions.
2. Generate SimPoint analysis using SimPoint 3.2 from UCSD.
(SimPoint 3.2 not included with this flow.)
3. To take gem5 checkpoints based on SimPoint analysis, use the
following option:
--take-simpoint-checkpoint=<simpoint file path>,<weight file
path>,<interval length>,<warmup length>
<simpoint file> and <weight file> is generated by SimPoint analysis
tool from UCSD. SimPoint 3.2 format expected. <interval length> and
<warmup length> are in number of instructions.
4. To resume from gem5 SimPoint checkpoints, use the following option:
--restore-simpoint-checkpoint -r <N> --checkpoint-dir <simpoint
checkpoint path>
<N> is (SimPoint index + 1). E.g., "-r 1" will resume from SimPoint
#0.
Both options accept template which will, through python string formatting,
have "mem", "disk", and "script" values substituted in from the mdesc.
Additional values can be used on a case by case basis by passing them as
keyword arguments to the fillInCmdLine function. That makes it possible to
have specialized parameters for a particular ISA, for instance.
The first option lets you specify the template directly, and the other lets
you specify a file which has the template in it.
In fs.py the io port controller was being attached to the iobus multiple
times. This should be done only once. In se.py, the the option use_map
was being set which no longer exists.
Mwait works as follows:
1. A cpu monitors an address of interest (monitor instruction)
2. A cpu calls mwait - this loads the cache line into that cpu's cache.
3. The cpu goes to sleep.
4. When another processor requests write permission for the line, it is
evicted from the sleeping cpu's cache. This eviction is forwarded to the
sleeping cpu, which then wakes up.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
Ruby's functional accesses are not guaranteed to succeed as of now. While
this is not a problem for the protocols that are currently in the mainline
repo, it seems that coherence protocols for gpus rely on a backing store to
supply the correct data. The aim of this patch is to make this backing store
configurable i.e. it comes into play only when a particular option:
--access-backing-store is invoked.
The backing store has been there since M5 and GEMS were integrated. The only
difference is that earlier the system used to maintain the backing store and
ruby's copy was write-only. Sometime last year, we moved to data being
supplied supplied by ruby in SE mode simulations. And now we have patches on
the reviewboard, which remove ruby's copy of memory altogether and rely
completely on the system's memory to supply data. This patch adds back a
SimpleMemory member to RubySystem. This member is used only if the option:
access-backing-store is set to true. By default, the memory would not be
accessed.
This patch is the final in the series. The whole series and this patch in
particular were written with the aim of interfacing ruby's directory controller
with the memory controller in the classic memory system. This is being done
since ruby's memory controller has not being kept up to date with the changes
going on in DRAMs. Classic's memory controller is more up to date and
supports multiple different types of DRAM. This also brings classic and
ruby ever more close. The patch also changes ruby's memory controller to
expose the same interface.
Both ruby and the system used to maintain memory copies. With the changes
carried for programmed io accesses, only one single memory is required for
fs simulations. This patch sets the copy of memory that used to reside
with the system to null, so that no space is allocated, but address checks
can still be carried out. All the memory accesses now source and sink values
to the memory maintained by ruby.
This changes the default ARM system to a Versatile Express-like system that supports
2GB of memory and PCI devices and updates the default kernels/file-systems for
AArch64 ARM systems (64-bit) to support up to 32GB of memory and PCI devices. Some
platforms that are no longer supported have been pruned from the configuration files.
In addition a set of 64-bit ARM regressions have been added to the regression system.
The bare-metal configuration option still configured memory with the old scheme
that no-longer works. This change unifies the code so there aren't any differences.
This patch adds the ability to load in config.ini files generated from
gem5 into another instance of gem5 built without Python configuration
support. The intended use case is for configuring gem5 when it is a
library embedded in another simulation system.
A parallel config file reader is also provided purely in Python to
demonstrate the approach taken and to provided similar functionality
for as-yet-unknown use models. The Python configuration file reader
can read both .ini and .json files.
C++ configuration file reading:
A command line option has been added for scons to enable C++ configuration
file reading: --with-cxx-config
There is an example in util/cxx_config that shows C++ configuration in action.
util/cxx_config/README explains how to build the example.
Configuration is achieved by the object CxxConfigManager. It handles
reading object descriptions from a CxxConfigFileBase object which
wraps a config file reader. The wrapper class CxxIniFile is provided
which wraps an IniFile for reading .ini files. Reading .json files
from C++ would be possible with a similar wrapper and a JSON parser.
After reading object descriptions, CxxConfigManager creates
SimObjectParam-derived objects from the classes in the (generated with this
patch) directory build/ARCH/cxx_config
CxxConfigManager can then build SimObjects from those SimObjectParams (in an
order dictated by the SimObject-value parameters on other objects) and bind
ports of the produced SimObjects.
A minimal set of instantiate-replacing member functions are provided by
CxxConfigManager and few of the member functions of SimObject (such as drain)
are extended onto CxxConfigManager.
Python configuration file reading (configs/example/read_config.py):
A Python version of the reader is also supplied with a similar interface to
CxxConfigFileBase (In Python: ConfigFile) to config file readers.
The Python config file reading will handle both .ini and .json files.
The object construction strategy is slightly different in Python from the C++
reader as you need to avoid objects prematurely becoming the children of other
objects when setting parameters.
Port binding also needs to be strictly in the same port-index order as the
original instantiation.
This patch moves code for instantiating a single memory controller from
the function config_mem() to a separate function. This is being done
so that memory controllers can be instantiated without assuming that
they will be attached to the system in a particular fashion.
