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[69.172.146.21]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70423f4a849sm5174072b3a.153.2024.06.11.00.51.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Jun 2024 00:51:18 -0700 (PDT) From: Tony Ambardar X-Google-Original-From: Tony Ambardar Date: Tue, 11 Jun 2024 00:51:16 -0700 To: Arnaldo Carvalho de Melo Cc: Mark Wielaard , Hengqi Chen , Mark Wielaard , Ying Huang , bpf@vger.kernel.org, dwarves@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Subject: Re: elfutils DWARF problem was: Re: Problem with BTF generation on mips64el Message-ID: References: <20240603191833.GD4421@gnu.wildebeest.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Jun 10, 2024 at 11:36:54PM -0700, Tony Ambardar wrote: > On Mon, Jun 03, 2024 at 08:47:24PM -0700, Tony Ambardar wrote: > > [snip] > > Arnaldo: > > Your stepping through DWARF/reloc diagnostics earlier was helpful. Thanks! > I reran your tests with the updated elfutils and latest pahole (pre-1.27), > and then found: > > - everything that worked before, still works > - your observations from "btfdiff vmlinux" and 'struct dma_chan' persist > - we now see expected output from "eu-readelf -winfo netdevsim.ko" > > Regarding pahole, DWARF parsing and BTF generation now works: > (with no more die__process: error messages seen) > > kodidev:~/linux$ pahole -F dwarf netdevsim.ko |wc -l > 14504 > > but strangely pahole still doesn't read its own generated BTF: > > kodidev:~/linux$ pahole -F btf netdevsim.ko > libbpf: Invalid BTF string section > pahole: file 'netdevsim.ko' has no btf type information. After staring at this I realized that this is split BTF and we needed to issue "pahole -F btf --btf_base vmlinux netdevsim.ko", which does work. Unfortunately, the libbpf error message is a bit cryptic; perhaps a future update could mention "--btf_base"? > > [snip] > > Many thanks everyone for your help, > Tony > > [1]: https://patchwork.sourceware.org/project/elfutils/list/?series=31601 > [2]: https://patchwork.sourceware.org/project/elfutils/list/?series=34310 > [3]: > https://github.com/guidosarducci/elfutils/commits/main-fix-mips-support-reloc/