add macro to control the bpf read method #27
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| #define PRINT_SKB_STR_SIZE 2048 | ||
| #define PRINT_SKB_STR_SIZE 2048 | ||
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| extern u32 LINUX_KERNEL_VERSION __kconfig; |
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I think LINUX_KERNEL_VERSION is set only when loading with libbpf (we are using github.com/cilium/ebpf to load the prog).
We could ask / contribute to cilium/ebpf to add the support for it (should be relatively trivial, see https://github.com/libbpf/libbpf/blob/v0.5.0/src/libbpf.c#L6804). /cc @ti-mo @lmb
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LINUX_KERNEL_VERSION is just to extract a running kernel version or a name that matches one of Kconfig’s keys. I do not think it has something with libbpf.
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The version is set during the loadtime. Check https://github.com/libbpf/libbpf/blob/v0.5.0/src/libbpf.c#L6804 to see how it's set in libbpf. Currently, cilium/ebpf doesn't support it.
Also, you can check it by adding into the code:
#if (LINUX_KERNEL_VERSION >= KERNEL_VERSION(5,5,0))
char fmt[] = "foo\n";
bpf_trace_printk(foo, sizeof(foo));
#endif
and then
cat /sys/kernel/debug/tracing/trace_pipe
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@brb thanks for you explanation. I got the point.
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👍 Please let me know if you are going to work on adding LINUX_KERNEL_VERSION support to cilium/ebpf.
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Great, apparenly this depends on parsing /proc/config.gz: https://nakryiko.com/posts/bpf-core-reference-guide/#linux-kernel-version. I don't think cilium/ebpf has support for Kconfig externs yet.
We have kernel version detection, though: https://github.com/cilium/ebpf/blob/1eb0e981058a2d5335965c6dc450a6442ad0377e/internal/version.go#L90-L99. I would prefer to use this for LINUX_KERNEL_VERSION over parsing kconfig.gz in the mean time.
@lmb any thoughts?
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apparenly this depends on parsing /proc/config.gz
It depends on config.gz for CONFIG_ parsing. While LINUX_KERNEL_VERSION - on the uname syscall.
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Okay, we're open to implementing the LINUX_KERNEL_VERSION extern using the existing kernel version detection we have in the lib. @zhangbo1882 would you be willing to contribute this as a feature?
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@ti-mo , I am very pleased to do that. Let me check cilium/ebpf code first.
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Closing due to inactivity. |
#21