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The implementation is based on sc_event sensitivities. Also of note is that the way reset works in the Accellera implementation isn't consistent with the spec. That says that wait(int n) is supposed to be equivalent to calling wait() n times, assuming n is greater than 0. Instead, Accellera stores that count and then doesn't wake up the process until the count is 0, decrementing it otherwise. That means that when the process is in reset, it won't actually reset for those intermediate wait()s which it would if wait() was called repeatedly. Also, oddly, when a reset becomes asserted, it will clear the count to 0 explicitly. That may have been an attempt to make the behavior of wait(int n) match the spec, but it doesn't handle cases where the reset is already set when wait(int n) is called. Change-Id: I92f8e9a128e6618af94dc048ce570a4436e17e4b Reviewed-on: https://gem5-review.googlesource.com/c/13186 Reviewed-by: Gabe Black <gabeblack@google.com> Maintainer: Gabe Black <gabeblack@google.com>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/Introduction, and for more information about building the simulator and getting started please see http://www.gem5.org/Documentation and http://www.gem5.org/Tutorials. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, SWIG, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/Dependencies for more details concerning the minimum versions of the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of ALPHA, ARM, NULL, MIPS, POWER, SPARC, or X86. This will build an optimized version of the gem5 binary (gem5.opt) for the the specified architecture. See http://www.gem5.org/Build_System for more details and options. With the simulator built, have a look at http://www.gem5.org/Running_gem5 for more information on how to use gem5. The basic source release includes these subdirectories: - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you will need compiled system firmware (console and PALcode for Alpha), kernel binaries and one or more disk images. Please see the gem5 download page for these items at http://www.gem5.org/Download If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.