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Previously, all abstract memory backed by the same physical memory will use the exact same chunk of shared memory if sharedBackstore is set. It means that all abstract memories, despite setting to a different range, will still be map to the same chunk of memory. As a result, setting the sharedBackstore not only allows our host system to share gem5 memory, it also enforces multiple gem5 memories to share the same content. Which will significantly affect the simulation result. Furthermore, the actual size of the shared memory will be determined by the last backingStore created. If the last one is unfortunately smaller than any previous backingStore, this may invalid previous mapped region and cause a SIGBUS upon access (on linux). In this CL, we put all backingStores of those abstract memories side by side instead of stacking them all together. So the behavior of abstract memories will be kept consistent whether the sharedBackstore is set or not, yet presist the ability to access those memories from host. Change-Id: Ic4ec25c99fe72744afaa2dfbb48cd0d65230e9a8 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57369 Reviewed-by: Yu-hsin Wang <yuhsingw@google.com> Reviewed-by: Gabe Black <gabe.black@gmail.com> Maintainer: Gabe Black <gabe.black@gmail.com> Tested-by: kokoro <noreply+kokoro@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/about, and for more information about building the simulator and getting started please see http://www.gem5.org/documentation and http://www.gem5.org/documentation/learning_gem5/introduction. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/documentation/general_docs/building for more details concerning the minimum versions of these tools. Once you have all dependencies resolved, type 'scons build/<CONFIG>/gem5.opt' where CONFIG is one of the options in build_opts like ARM, NULL, MIPS, POWER, SPARC, X86, Garnet_standalone, etc. This will build an optimized version of the gem5 binary (gem5.opt) with the the specified configuration. See http://www.gem5.org/documentation/general_docs/building for more details and options. The main source tree includes these subdirectories: - build_opts: pre-made default configurations for gem5 - build_tools: tools used internally by gem5's build process. - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - include: include files for use in other programs - site_scons: modular components of the build system - 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 may need compiled system firmware, kernel binaries and one or more disk images, depending on gem5's configuration and what type of workload you're trying to run. Many of those resources can be downloaded from http://resources.gem5.org, and/or from the git repository here: https://gem5.googlesource.com/public/gem5-resources/ If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.