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When checking whether a given option is supported, we try to compile or link a small test program and see if that succeeded or not. There are some options which are not really supported, but if you use them the compiler might produce an error instead of failing to build. An example of that is clang (version 9 at least) which will warn if you try to disabled a warning it doesn't know about. On the develop branch, this is fine since we have werror enabled, and even these warnings will prevent the options from being enabled. On the release branches where we disable werror for better future compatibility, this causes a problem because these options still pass the test and end up being enabled. This doesn't break the build, but can cause a bunch of annoying and unnecessary warnings which clutter up the build output. To remove this inconsistency, we can enable werror just for the test compiles or links which decide whether or not an option is supported. That won't necessarily differentiate *why* a warning was generated, so if through some strange combination of circumstances something else causes a warning pervasively through the build, then this may think an option is to blame and not enable it even though it's fine. This seems unlikely though, and not worth worrying about without a specific example showing that it can/will actually happen. Change-Id: I6a1e3273c0b646a5636dc9986c70dcd5332f6f64 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54624 Maintainer: Gabe Black <gabeblack@google.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
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.