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Currently, if the remote gdb stub fails to read a byte from an incoming packet because the connection has been dropped, the read call will return anyway and the calling code will have no way to know something bad happened. It might reattempt the read over and over again waiting for some particular byte, doomed to never make forward progress. This change modifies the remote GDB code so that if a read or write call fails, it will instead detach from the debugger and continue. Before this change, When simulating a port scan, ie connecting to the debugger port and then immediately dropping the connection using this command: nc -v -n -z -w 1 127.0.0.1 7000 gem5 would enter the previously described death spiral. After it, gem5 detaches from the bad connection and resumes execution. Subsequently attaching with gdb was successful. This code is written in a C centric style, and would benefit from some refactoring. Change-Id: Ie3c0bb35b9cfe3671d0f731e3907548bae0d292f Reviewed-on: https://gem5-review.googlesource.com/3180 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.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.