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Saturday, February 20 • 2:00pm - 2:25pm
Always present type information thanks to BPF: BTF

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The presence of compact type information brought initially by the needs of BPF
allows for more and more tools to use it seamlessly.

This talk will show what has been accomplished so far in the BTF (BPF Type
Information) camp, from improvements in its generation from DWARF, overcoming
compiler bugs and speeding up the tool used to encode the kernel BTF
information, pahole.

The kernel now has all its types always available at /sys/kernel/btf/vmlinux
and at devconf.cz 2021 time all its modules will be in that sysfs hierarchy
with the advent of split BTF.

The new raw pretty printing features of pahole will be demonstrated, where
things like raw arrays of structs can be fed to it plus the type name to use in
decoding stdin, all sorts of heuristics and back references are used to grok
complex data files.

The kernel also now have snprintf routines that use BTF for use in debugging
and tracing, bpftrace and bpftool use it and examples of such usage will be

avatar for Arnaldo Melo

Arnaldo Melo

Senior Principal Software Engineer, Red Hat Inc.
Maintained IPX, LLC, Appletalk protocols. Refactored the TCP/IP stack to reuse non TCP specific parts. Implemented the Linux DCCP stack. Created pahole, a tool to help in optimizing data structures, used in Linux, glibc, KDE, xine & others. Maintainer of ‘perf’ (profiling, tracing... Read More →

Saturday February 20, 2021 2:00pm - 2:25pm CET
Session Room 1