Create a folder with common mistakes for beginners

[mandrei12]

In this folder we will include common mistakes and missconceptions about the way we use Unikraft/kraft and try to also offer some solutions to them.

Signed-off-by: Andrei Mutu [email protected]

[razvand]

I'm adding here draft items to add to the PR:

• The socat issue appearing on Ubuntu 20.04. The solution is to install a newer version, either as a Debian package or from source. Instructions that we tested to work for source-based installation:

  $ wget http://www.dest-unreach.org/socat/download/socat-1.7.4.4.tar.gz
  $ tar xzf socat-1.7.4.4.tar.gz 
  $ cd socat-1.7.4.4/
  $ ./configure
  $ make
  $ sudo make install 
  

• ARM64 compilation fails for GCC >= 10. It errors on the absence of __getauxval:

  /usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: warning: -z relro ignored
  OBJCOPY helloworld_kvm-arm64.o
  LD      helloworld_kvm-arm64.dbg
  /usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: warning: -z relro ignored
  /usr/lib/gcc-cross/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/bin/ld: /home/mohamed/Desktop/Code/OS/apps/helloworld/build/helloworld_kvm-arm64.o: in function init_have_lse_atomics':
  lse-init.o:(.text.startup+0xbc): undefined reference to __getauxval'
  lse-init.o:(.text.startup+0xbc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol __getauxval'
  collect2: error: ld returned 1 exit status
  make[3]:  [/home/mohamed/.unikraft/unikraft/plat/kvm/Linker.uk:24: /home/mohamed/Desktop/Code/OS/apps/helloworld/build/helloworld_kvm-arm64.dbg] Error 1
  make[2]:  [Makefile:984: sub-make] Error 2
  make[1]:  [Makefile:32: _all] Error 2
  make[1]: Leaving directory '/home/mohamed/.unikraft/unikraft'
  make:  [Makefile:6: all] Error 2`
  

  The solution is to use GCC <= 9.

• If you don't have KVM enable, kraft won't run. There is no option to run kraft and disable KVM. If that is the case you need to run manually using qemu-system-x86_64 (without the -enable-kvm) option, or using qemu-guest.

  Could not access KVM kernel module: No such file or directory
  qemu-system-x86_64: failed to initialize kvm: No such file or directory
  

  Check with:

  lsmod | grep kvm
  

  Check virtualization availability:

  lscpu | grep '\(vmx\|svm\)'
  

• build/uk-gdb.py has to be run inside GDB, not on the shell:

  root@d81c14b42759:/workdir/apps/helloworld# source build/uk-gdb.py 
  bash: import: command not found
  bash: import: command not found
  bash: import: command not found
  bash: import: command not found
  bash: scripts_dir: command not found
  bash: build/uk-gdb.py: line 39: syntax error near unexpected token `scripts_dir'
  bash: build/uk-gdb.py: line 39: `sys.path.append(scripts_dir)'
  root@d81c14b42759:/workdir/apps/helloworld# 
  

• kraft list update fails. You need to create a personal access token with public_repo only. And use UK_KRAFT_GITHUB_TOKEN=TODO kraft list update (replace TODO with developer token).

• qemu-system-x86_64: -gdb tcp:🔢 Failed to find an available port: Address already in use - You have another QEMU instance started somewhere. Close it. You could also use sudo pkill -f qemu (be careful when using it, it will terminate all QEMU processes).

• You need a large enough screen for make menuconfig or kraft menuconfig. Make your terminal screen larger if you get the error below:

  make[1]: Entering directory '/home/mohamed/.unikraft/unikraft'
  Your display is too small to run Menuconfig!
  It must be at least 19 lines by 80 columns.
  make[3]: *** [/home/mohamed/Desktop/Code/OS/apps/helloworld/build/Makefile:834: menuconfig] Error 1
  make[2]: *** [Makefile:984: sub-make] Error 2
  make[1]: *** [Makefile:32: _all] Error 2
  make[1]: Leaving directory '/home/mohamed/.unikraft/unikraft'
  make: *** [Makefile:9: menuconfig] Error 2
  

• Do a make clean or kraft clean before building Unikraft on a different architecture. Otherwise, you get the error:

  TODO
  

• Run ./.._kvm-x86_kvm - you can't run a KVM / QEMU image like an executable.

• Run qemu-system-x86_64 ...kvm-aarch64 - you can't run qemu-system-x86_64 on an aarch64 image. You need to run qemu-system-aarch64.

• Run GDB on another image.

• Start for debugging but use the basic image, not the .dbg image.

• Run qemu-system-aarch64 but omitting -machine and -cpu.

• Use -cpu host to remove warning.

• qemu: could not open kernel file ./build/app-helloworld_kvm-x86_64: Make sure the built image is indeed named app-helloworld_kvm-x86-64by runningls build/in your terminal. It may be named onlyhelloworld_kvm-x86_64`. Or you may have omitted to build it.

• Omitting to use UK_WORK_DIR for a custom kraft environment.

• Omitting the update of the LIBS variable in the Makefile.

• Omitting the clone of a library file in libs/ in a custom kraft environment.

• Unikraft core repository or library repository is on staging (or the proper branch). Do git status path/to/repository.

• Building for ARM64 fails:

  make[1]: Entering directory '/home/parallels/kraft_workdir/unikraft'
  /bin/bash: line 1: aarch64-linux-gnu-gcc: command not found
  /bin/bash: line 1: [: -gt: unary operator expected
  /bin/bash: line 1: [: -eq: unary operator expected
  /home/parallels/kraft_workdir/unikraft/arch/arm/arm64/Makefile.uk:77: *** Require GCC version >= 4.9 found ..  Stop.
  make[2]: *** [Makefile:1016: sub-make] Error 2
  make[1]: *** [Makefile:32: _all] Error 2
  make[1]: Leaving directory '/home/parallels/kraft_workdir/unikraft'
  make: *** [Makefile:6: all] Error 2
  

  You have to install the cross-compile toolchain for aarch64. TODO: instructions.

• kraft is installed for the current user and ~/.local/bin is not part of PATH.

• Issues with library ordering in Makefile.

[StefanJum]

Superseded by #391