Unable to run buildroot for gem5 with "No such file or directory build/X86/gem5.opt"

[GeoBK]

In reference to the answer here on stackoverflow - https://stackoverflow.com/questions/60942236/is-there-an-updated-disk-image-binary-for-the-x86-architecture-for-running-gem5 - Running the command ./build --download-dependencies gem5-buildroot and then running ./run --emulator gem5 the second command fails saying - "No such file or directory: '/home/bibin/projects/linux-kernel-module-cheat/out/gem5/default/build/X86/gem5.opt" Is there some additional command which needs to be run as well before running the gem5 emulator? I am running on an Ubuntu18.04.4 LTS system

[cirosantilli]

Hi geo,

Those two should be it.

Can you double check that the ./build command succeed without errors? When I do a ./build --dry-run it does show the gem5 build commands (search for gem5.opt), so it feels like the build failed for some reason.

[yunchih]

Gem5 failed to compile:

 [SO PARAM] PS2Device -> X86/params/PS2Device.hh
 [     CXX] X86/dev/x86/i8254.cc -> .o
In file included from /cheat/linux-kernel-module-cheat/out.docker/gem5/default/build/X86/base/stats/hdf5.cc:38:
/cheat/linux-kernel-module-cheat/out.docker/gem5/default/build/X86/base/stats/hdf5.hh:41:10: fatal error: H5Cpp.h: No such file or directory
 #include <H5Cpp.h>
          ^~~~~~~~~
compilation terminated

can be resolved by manually adding include directory into SConstruct:

main.Prepend(CPPPATH=Dir('/usr/include/hdf5/serial'))

[cirosantilli]

@yunchih thanks. The main scons attempts to take care of that and build works for me without patching: https://github.com/gem5/gem5/blob/9fc9c67b4242c03f165951775be5cd0812f2a705/SConstruct#L871 but maybe there's a case where it breaks.

[GeoBK]

I am not sure - but my theory right now is that my system might have run out of memory and therefore maybe it wasn't able to generate the gem5.opt file. I had around 17GB of free memory on that partition when I started the build. I'll try running the build again when I get access to that machine again (I cant physically access it right now with the quarantine and all)

[Jrebort]

@cirosantilli I have same question ./linux-kernel-module-cheat/out/gem5/default/build/X86 Gem5.opt does not seem to be generated here. I tried to run SConscript in this directory, but got the following error

./SConscript:45: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
  import imp
Traceback (most recent call last):
  File "./SConscript", line 56, in <module>
    from gem5_scons import Transform, warning, error
ModuleNotFoundError: No module named 'gem5_scons'

[cirosantilli]

@Jrebort I'm going to try that out. The first suspicion is python2 vs python3 issues due to more or less recent migration. What's your OS version/Python version?

[Jrebort]

@cirosantilli

@Jrebort I'm going to try that out. The first suspicion is python2 vs python3 issues due to more or less recent migration. What's your OS version/Python version?

/usr/bin/python -V Python 2.7.17

I checked the ./runfile, used /usr/bin/env python3 and printed the following information：

Python 3.8.3 (default, May 19 2020, 18:47:26) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()

[cirosantilli]

@Jrebort can you open an issue upstream with the raw scons build command, your OS version, Python version, error message: https://gem5.atlassian.net/jira/software/c/projects/GEM5/issues

I have gem5 compilation working on my Ubuntu 20.04 host in which python is now python3.

But I wasn't able to get it working on Ubuntu 20.04 Docker in this repo nicely easily now.

I think I needed to install python2 pip and the module six in Python2 on my host, and that required pyenv.

But upstream testing does seem to use docker and no Python2: https://askubuntu.com/questions/350475/how-can-i-install-gem5/1275773#1275773

ARGHH this Python 2 vs 3 is such a mess.

[cirosantilli]

I'm going to close this ticket for now, because the error message could be too many possibilities: it just means gem5 build failed, which there are many possible failures for.

At bbfa782736dfda014dd9b45f26315e0c666443e2 I've also made ./build stop on failures, which will make it much easier to notice them :-)

So if anyone gets this problem again, please check the more precise error cause in ./build-gem5 and open a separate issue for that so we can tackle it.