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Docs #315

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merged 2 commits into from Jan 4, 2019
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Docs #315

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b403169
recommend 4.9 kernels
brendangregg Jan 3, 2019
aea313e
add license in README
brendangregg Jan 3, 2019
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21 changes: 12 additions & 9 deletions INSTALL.md
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Expand Up @@ -13,7 +13,18 @@

# Linux Kernel Requirements

Your kernel needs to be built with the following options:
It is recommended that you are running a Linux 4.9 kernel or higher. Some tools may work on older kernels, but these old kernels are no longer tested. To explain this requirement, these are the kernel versions where major features were added:

- 4.1 - kprobes
- 4.3 - uprobes
- 4.6 - stack traces, count and hist builtins (use PERCPU maps for accuracy and efficiency)
- 4.7 - tracepoints
- 4.9 - timers/profiling

Minor improvements have been added in later kernels, so newer than 4.9 is preferred.

Your kernel also needs to be built with the following options:

```
CONFIG_BPF=y
CONFIG_BPF_SYSCALL=y
Expand All @@ -22,14 +33,6 @@ CONFIG_HAVE_EBPF_JIT=y
CONFIG_BPF_EVENTS=y
```

To use some BPFtrace features, minimum kernel versions are required:
- 4.1+ - kprobes
- 4.3+ - uprobes
- 4.6+ - stack traces, count and hist builtins (use PERCPU maps for accuracy and efficiency)
- 4.7+ - tracepoints
- 4.9+ - timers/profiling


# Building BPFtrace

# Ubuntu
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16 changes: 16 additions & 0 deletions README.md
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Expand Up @@ -291,3 +291,19 @@ See the [Reference Guide](docs/reference_guide.md) for more detail.
<center><a href="images/bpftrace_internals_2018.png"><img src="images/bpftrace_internals_2018.png" border=0 width=700></a></center>

bpftrace employs various techniques for efficiency, minimizing the instrumentation overhead. Summary statistics are stored in kernel BPF maps, which are asynchronously copied from kernel to user-space, only when needed. Other data, and asynchronous actions, are passed from kernel to user-space via the perf output buffer.

## License

Copyright 2019 Alastair Robertson

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.