diff --git a/study/kernel/00-DESCRIPTION/BPF.md b/study/kernel/00-DESCRIPTION/BPF.md
index 5ee2963..61856aa 100644
--- a/study/kernel/00-DESCRIPTION/BPF.md
+++ b/study/kernel/00-DESCRIPTION/BPF.md
@@ -106,7 +106,7 @@ raw_tracepoint 相比 tracepoint
 
 
 
-# libbpf-tools
+# 3 libbpf-tools
 -------
 
 
@@ -118,6 +118,21 @@ raw_tracepoint 相比 tracepoint
 
 [How to use libbpf-tools with ubuntu 18.04 4.15 kernel](https://www.gitmemory.com/issue/iovisor/bcc/3232/761744003)
 
+
+# 4 debuging
+-------
+
+[Dumping kernel data structures with BPF](https://lwn.net/Articles/818714)
+
+| 时间  | 作者 | 特性 | 描述 | 是否合入主线 | 链接 |
+|:----:|:----:|:---:|:----:|:---------:|:----:|
+| 2018/03/01 | Jan H. Schönherr | [bpf: implement bpf based dumping of kernel data structures](http://patches.linaro.org/cover/221148) | BPF 支持 raw tracepoint 跟踪, 提供了对 tracepoint 参数的访问. | v1 ☐ | [PatchWork v2](http://patches.linaro.org/cover/221148) |
+| 2020/06/23 | Alan Maguire <alan.maguire@oracle.com> | [bpf, printk: add BTF-based type printing](https://lore.kernel.org/patchwork/cover/1261591/) | 在 BPF 程序中通过 printk 打印内核结构体   | v3 ☐ | [PatchWork v3,bpf-next,0/8](https://lore.kernel.org/patchwork/cover/1261591/) |
+| 2020/08/06 | Alan Maguire <alan.maguire@oracle.com> | [bpf: add bpf-based bpf_trace_printk()-like support](https://lore.kernel.org/patchwork/cover/1285027) | 在 BPF 程序中通过 trace_printk 打印信息   | RFC ☐ | [PatchWork RFC,bpf-next,0/4](https://lore.kernel.org/patchwork/cover/1285027) |
+| 2020/09/28 | Alan Maguire <alan.maguire@oracle.com> | [bpf: add helpers to support BTF-based kernel data display](https://lore.kernel.org/patchwork/cover/1312835) | 在 BPF 程序中通过 printk 打印内核结构体   | v7 ☐ | [PatchWork v7,bpf-next,0/8](https://lore.kernel.org/patchwork/cover/1312835) |
+| 2021/06/19 | Alan Maguire <alan.maguire@oracle.com> | [libbpf: BTF dumper support for typed data](https://lore.kernel.org/patchwork/cover/1448989) | 引入 btf_dump__dump_type_data, 可以用来输出结构体的信息. | v5 ☐ | [PatchWork v5,bpf-next,0/3](https://lore.kernel.org/patchwork/cover/1448989) |
+
+
 <br>
 
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