[Qemu-devel] [Bug 1813010] Re: Parallel builds fail (make -j >=2) when using --extra-cflags "--save-temps"

[Peter Maydell]

Hi; I'm going to close this bug because there's no way that QEMU's build
process can handle being passed -save-temps via --extra-cflags, because
this will cause GCC to use the same output files for multiple different
source files, and they will clash. (Even with a non-parallel build, one
compile is going to win, and the temp files for the first compile of the
pair will just be overwritten and lost.)

As you've discovered, the right way to do this is to use -save-
temps=obj, which will correctly put the temporary files in different
places for each generated object file, so they don't conflict with each
other.


** Changed in: qemu
       Status: Confirmed => Invalid

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https://bugs.launchpad.net/bugs/1813010

Title:
  Parallel builds fail (make -j >=2) when using --extra-cflags "--save-
  temps"

Status in QEMU:
  Invalid

Bug description:
  specs:
  QEMU commit: 9f33051abce238ab43a23125e237aac8b0931b88
  # of Cores: 8
  Host kernel: Linux 4.19.16-1-lts
  Host type: x86_64 GNU/Linux
  Host distro: Archlinux
  Guest: we never get that far

  
  steps:
  # fresh copy of the latest commit
  > git clone https://git.qemu.org/git/qemu.git

  # separate build dir
  > mkdir build
  > cd build

  # sample configuration for riscv (this happens for other targets as well)
  > ../qemu/configure --target-list=riscv64-softmmu --enable-debug 
--extra-cflags='-O0 -g3 -save-temps' --prefix=/install/riscv-qemu

  # this will fail (see attached log file)
  > make -j 2

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