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Some cache techniques may need to move a block's metadata information into another block. This must have some limitations to avoid mistakes: - The destination entry must be invalid, otherwise the replacement policy steps would be skipped. - The source entry must be valid, otherwise there would be no point in moving their metadata contents. - The entries locations (set, way, offset...) must not be moved, since they are fixed. The same principle is applied to the location specific variables, such as the replacement pointer Why it would be used: For example, when using compression, and a block goes from uncompressed to compressed state due to an overwrite, after the tag lookup (sequential access) it can be decided whether to store the new data in the old location, or, since we might have already found the block's co- allocatable blocks, move it to co-allocate. Other examples of techniques that could use this functionality are Skewed Compressed Caches, and ZCaches. Change-Id: I96e4f8cc8c992c4b01f315251d1a75d51c28692c Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36575 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@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.