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The logic that determines which syscall to call was built into the implementation of faults/exceptions or even into the instruction decoder, but that logic can depend on what OS is being used, and sometimes even what version, for example 32bit vs. 64bit. This change pushes that logic up into the Process objects since those already handle a lot of the aspects of emulating the guest OS. Instead, the ISA or fault implementations just notify the rest of the system that a nebulous syscall has happened, and that gets propogated upward until the process does something with it. That's very analogous to how a system call would work on a real machine. When a system call happens, the low level component which detects that should call tc->syscall(&fault), where tc is the relevant thread (or execution) context, and fault is a Fault which can ultimately be set by the system call implementation. The TC implementor (probably a CPU) will then have a chance to do whatever it needs to to handle a system call. Currently only O3 does anything special here. That implementor will end up calling the Process's syscall() method. Once in Process::syscall, the process object will use it's contextual knowledge to determine what system call is being requested. It then calls Process::doSyscall with the right syscall number, where doSyscall centralizes the common mechanism for actually retrieving and calling into the system call implementation. Jira Issue: https://gem5.atlassian.net/browse/GEM5-187 Change-Id: I937ec1ef0576142c2a182ff33ca508d77ad0e7a1 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23176 Maintainer: Gabe Black <gabeblack@google.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Brandon Potter <Brandon.Potter@amd.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.