1 files changed, 62 insertions, 0 deletions
diff --git a/results/classifier/118/device/1898 b/results/classifier/118/device/1898
new file mode 100644
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--- /dev/null
+++ b/results/classifier/118/device/1898
@@ -0,0 +1,62 @@
+device: 0.845
+graphic: 0.773
+performance: 0.701
+permissions: 0.701
+vnc: 0.674
+ppc: 0.641
+architecture: 0.619
+files: 0.618
+risc-v: 0.590
+kernel: 0.560
+PID: 0.533
+VMM: 0.485
+socket: 0.465
+network: 0.448
+boot: 0.437
+debug: 0.431
+user-level: 0.409
+register: 0.394
+TCG: 0.361
+peripherals: 0.348
+semantic: 0.334
+arm: 0.285
+mistranslation: 0.256
+assembly: 0.199
+x86: 0.099
+i386: 0.099
+hypervisor: 0.098
+virtual: 0.095
+KVM: 0.057
+
+Ninja makeserver support
+Description of problem:
+Building `qemu` using a patched version of `ninja`[0] to utilize `make`'s jobserver feature doesn't work when building `qemu`. Usually, when using a jobserver to control the number of jobs being built in parallel across multiple different builds (i.e. when building with `open-embedded` or `buildroot`), the `-j$(nproc)` argument is left out. In this case, the `Qemu` `Makefile` interprets the absent `-j` argument as a wish for a single process only, and adds a `-j1` argument to the `ninja` call.
+Steps to reproduce:
+1. Built/install the patched `ninja` from [0]: `export PATH=<path/to/ninja>:$PATH`
+2. Start the attached [jobserver.py](/uploads/8215e8a470c97cd456d2d14e2c71c6a5/jobserver.py) script: `python jobserver.py /tmp/jobserver 4`
+3. Configure `qemu`: `mkdir build; ../configure`
+4. Build `qemu`: `MAKEFLAGS="--jobserver-auth=fifo:/tmp/jobserver" make`
+5. Observe that only a single CPU/core is being used.
+
+Now, to avoid passing `-j1` to `ninja`, remove filtering of `-j` arguments from the `Makefile`:
+
+```patch
+diff --git a/Makefile b/Makefile
+index bfc4b2c8e9..d66141787e 100644
+--- a/Makefile
++++ b/Makefile
+@@ -142,7 +142,6 @@ MAKE.k = $(findstring k,$(firstword $(filter-out --%,$(MAKEFLAGS))))
+ MAKE.q = $(findstring q,$(firstword $(filter-out --%,$(MAKEFLAGS))))
+ MAKE.nq = $(if $(word 2, $(MAKE.n) $(MAKE.q)),nq)
+ NINJAFLAGS = $(if $V,-v) $(if $(MAKE.n), -n) $(if $(MAKE.k), -k0) \
+-        $(filter-out -j, $(lastword -j1 $(filter -l% -j%, $(MAKEFLAGS)))) \
+         -d keepdepfile
+ ninja-cmd-goals = $(or $(MAKECMDGOALS), all)
+ ninja-cmd-goals += $(foreach g, $(MAKECMDGOALS), $(.ninja-goals.$g))
+```
+
+Run the build again, and see four jobs being run in parallel:
+
+`make clean; MAKEFLAGS="--jobserver-auth=fifo:/tmp/jobserver" make`
+Additional information:
+[0] https://github.com/stefanb2/ninja/tree/topic-issue-1139-part-3-jobserver-fifo