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This removes the sync between the thread contexts on m5ops. This works for some m5 ops, but not others. It's needed for m5_readfile, which I use. See also: http://reviews.gem5.org/r/2774/
This patch makes kvm work for both Intel and AMD CPUs. See http://reviews.gem5.org/r/2613/
I really have no idea what's in the changeset. But it seems to be required to get KVM to work on the CSL machines with RHEL6. Patch is from Nilay.
Previously, before a CPU was switched out, the TLB was always flushed Now, we first call takeOverFrom with the TLB. We only flush the TLB right before the CPU is switched in. This changeset also contains the needed code for x86 to takeOverFrom with the TLB, similar changes may be needed for the ARM architecture. With this changeset, when you switch from atomic to timing mode the TLB is warm.
Previously, when forking, the thread states were inconsistent. Now, after a fork, we re-create all the needed threads. This allows you to run in *single-threaded* mode after a fork. There would need to be a way to migrate the threads to conintue in threaded mode.
This adds a couple of example config files for using kvm and sampling. Additionally, it adds a set of python files similar to the simple FS configs from Learning gem5.
simply moved around code from original sample_2d.py
the Sample() function for simulating at a single sample point and sampleROI() wrapper. The example script sample_2d.py shows the usage of sampleROI()
made changes to the library so generateSamples() is more generic
sample_one_var.py gives an example of doing online stats. The key idea with this sample script is to run as many simulations at a sample point to hit a pre-defined bound on the error in the estimated mean.
1. Added better documentation for the example scripts 2. Minor bug fixes 3. Miscellaneous changes
…5 into devel/sampling
…and memory controller. This is used for adding random perturbations for the purpose of sampling. The max memory delay can be set using the --max_random_delay
…5 into devel/sampling
Author
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Added the sampling utilities - util/sampling/tardis_analysis.py |
powerjg
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Aug 21, 2025
Apply construct-on-first-use scheme to address this issue.
==2940471==ERROR: AddressSanitizer: initialization-order-fiasco on address 0x00001bd22044 at pc 0x0000045b8041 bp 0x7ffefca16730 sp 0x7ffefca16728
READ of size 4 at 0x00001bd22044 thread T0
#0 0x0000045b8040 in gem5::DrainManager::state() const gem5/sim/drain.hh:152
#1 0x0000045b8040 in gem5::Drainable::Drainable() gem5/sim/drain.cc:199
#2 0x000004790b13 in gem5::SimObject::SimObject() gem5/sim/sim_object.cc:71
#3 0x000000926dee in DefaultRequestPort gem5/mem/port.cc:67
#4 0x000000926dee in __static_initialization_and_destruction_0 gem5/mem/port.cc:110
#5 0x000000926dee in _GLOBAL__sub_I__ZN4gem511RequestPortC2ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEPNS_9SimObjectEs gem5/mem/port.cc:208
gem5#6 0x7fd81e6b6eba in call_init ../csu/libc-start.c:145
powerjg
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We can remedy this with proper initializations. The offending variable was
TargetList's canMergeWrites, but I also fixed up everything in MSHR.
gem5/mem/cache/mshr.hh:169:11: runtime error: load of value 8, which is not a valid value for type 'bool'
#0 0x000003e0a992 in gem5::MSHR::TargetList::TargetList(gem5::MSHR::TargetList const&) gem5/mem/cache/mshr.hh:169
#1 0x000003e0b84c in gem5::MSHR::MSHR(gem5::MSHR const&) gem5/mem/cache/mshr.hh:74
#2 0x000003e0d83b in void std::_Construct<gem5::MSHR, gem5::MSHR const&>(gem5::MSHR*, gem5::MSHR const&) /spec/compilers/gcc-15.1.0/include/c++/15.1.0/bits/stl_construct.h:133
#3 0x000003e0d83b in gem5::MSHR* std::__do_uninit_fill_n<gem5::MSHR*, unsigned long, gem5::MSHR>(gem5::MSHR*, unsigned long, gem5::MSHR const&) /spec/compilers/gcc-15.1.0/include/c++/15.1.0/bits/stl_uninitialized.h:470
powerjg
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Mar 9, 2026
Static storage duration objects that has non-trivial destructor are bad. And a function-local static reference of the form static T& t = *new T; is allowed Reference for the style guide: https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables Background: There's a segmentation fault on the arm server if I run the gem5 simulation with --dry-run, do m5.instantiation() but no m5.simulation(). Stack trace: Thread 1 "gem5.opt" received signal SIGSEGV, Segmentation fault. __GI_strcmp () at ../sysdeps/aarch64/strcmp.S:136 warning: 136 ../sysdeps/aarch64/strcmp.S: No such file or directory (gdb) bt #0 __GI_strcmp () at ../sysdeps/aarch64/strcmp.S:136 #1 0x0000aaaab415f424 in sc_gem5::(anonymous namespace)::findEventIn (events=std::vector of length 2, capacity 2 = {...}, name="event_0") at /usr/include/c++/14/bits/basic_string.h:227 #2 sc_gem5::(anonymous namespace)::popEvent (events=0xaaaac00aed50 <sc_gem5::topLevelEvents()::topLevelEvents>, name="event_0") at src/systemc/core/event.cc:68 #3 sc_gem5::Event::~Event (this=0xaaaac1d8b000, __in_chrg=<optimized out>) at src/systemc/core/event.cc:150 #4 0x0000aaaab417e95c in sc_core::sc_event::~sc_event (this=<optimized out>, __in_chrg=<optimized out>) at src/systemc/core/sc_event.cc:321 #5 0x0000aaaabf7b39e0 in scx::async_request::~async_request() () gem5#6 0x0000aaaabf7b12d4 in scx::scheduler_mapping::~scheduler_mapping() () gem5#7 0x0000aaaabf7b1498 in scx::scheduler_mapping::~scheduler_mapping() () gem5#8 0x0000aaaabf7adfb4 in scx::scx_simcontroller::~scx_simcontroller() () gem5#9 0x0000ffffe7b5946c in __run_exit_handlers (status=0, listp=0xffffe7cd0660 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true) at ./stdlib/exit.c:118 gem5#10 0x0000ffffe7b59560 [PAC] in __GI_exit (status=<optimized out>) at ./stdlib/exit.c:148 gem5#11 0x0000ffffe7b42220 [PAC] in __libc_start_call_main (main=main@entry=0xaaaab6af43a0 <main(int, char**)>, argc=argc@entry=15, argv=argv@entry=0xffffffffeee8) at ../sysdeps/nptl/libc_start_call_main.h:74 gem5#12 0x0000ffffe7b422fc [PAC] in __libc_start_main_impl (main=0xaaaab6af43a0 <main(int, char**)>, argc=15, argv=0xffffffffeee8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=<optimized out>) at ../csu/libc-start.c:360 gem5#13 0x0000aaaab4003b30 [PAC] in _start () The issue seems to be the destruction order. There's a static topLevelEvents() that will be used in Event() ctor with sc_event. The segmentation fault happens when topLevelEvents already be destruct before ~Event calling destructor that will use topLevelEvents.
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