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can optimize out trace events completely. This is the default and imposes no |
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performance penalty. |
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=== Stderr === |
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The "stderr" backend sends trace events directly to standard error. This |
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effectively turns trace events into debug printfs. |
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This is the simplest backend and can be used together with existing code that |
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uses DPRINTF(). |
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=== Simpletrace === |
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The "simple" backend supports common use cases and comes as part of the QEMU |
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trace backends but it is portable. This is the recommended trace backend |
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unless you have specific needs for more advanced backends. |
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=== Stderr ===
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The "stderr" backend sends trace events directly to standard error output
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during emulation.
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Warning: the "simple" backend is not thread-safe so only enable trace events
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that are executed while the global mutex is held. Much of QEMU meets this |
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requirement but some utility functions like qemu_malloc() or thread-related
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code cannot be safely traced using the "simple" backend.
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==== Monitor commands ==== |
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The "ust" backend uses the LTTng Userspace Tracer library. There are no |
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monitor commands built into QEMU, instead UST utilities should be used to list, |
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enable/disable, and dump traces. |
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=== SystemTap === |
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The "dtrace" backend uses DTrace sdt probes but has only been tested with |
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SystemTap. When SystemTap support is detected a .stp file with wrapper probes |
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is generated to make use in scripts more convenient. This step can also be |
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performed manually after a build in order to change the binary name in the .stp |
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probes: |
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scripts/tracetool --dtrace --stap \ |
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--binary path/to/qemu-binary \ |
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--target-type system \ |
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--target-arch x86_64 \ |
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<trace-events >qemu.stp |
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