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As mentioned on the JIRA issue, uncacheable requests done after cacheable requests had been done to the address make the cache writeback and write trash data to memory. We believe that the kernel must be doing earlier invalidation by set and way earlier on to prevent this, but that is not implemented in gem5 yet. The problem can be worked around by booting in atomic without caches and checkpointing after init, because uncacheable accesses are only done on early stages of CPU bringup, which is the more common use case anyways. The aarch64 Linux kernel developers have stated that set and way invalidates are not going to be used in aarch64, which further reduces the importance of implementing this immediatly JIRA: https://gem5.atlassian.net/browse/GEM5-640 Change-Id: Ieba31e707dcc09693d7a87ed9d51c3d1ffa3abe0 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33015 Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Maintainer: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.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, SWIG, 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 the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of 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/documentation/general_docs/building for more details and options. 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. If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.