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[67.170.74.237]) by smtp.gmail.com with ESMTPSA id m1-20020a62f201000000b006ddc03c425bsm8004664pfh.180.2024.01.30.09.27.37 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Jan 2024 09:27:38 -0800 (PST) From: dthaler1968@googlemail.com X-Google-Original-From: To: "'bpf'" , Subject: ISA: BPF_CALL | BPF_X Date: Tue, 30 Jan 2024 09:27:36 -0800 Message-ID: <076001da53a1$9ebfa210$dc3ee630$@gmail.com> 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-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Content-Language: en-us Thread-Index: AdpTn/i/+Jdzpl/jQ0iLyOHFFXfaaQ== clang generates BPF code with opcode 0x8d (BPF_CALL | BPF_X, which it calls "callx"), when compiling with -O0 or -O1. Of course -O2 is recommended, but if anyone later defines opcode 0x8d for anything other than what clang means by it, it could cause problems. On the BPF_MSH thread at https://mailarchive.ietf.org/arch/msg/bpf/ogmS9qFhdBCxC4VrOWL7nzjSiXU/ Alexei wrote regarding BPF_ABS and BPF_IND: > DW never existed in classic bpf, so abs/ind never had DW flavor. > If some assembler/compiler decided to "support" them it's on them. > The standard must not list such things as deprecated. They never existed. Technically BPF_CALL | BPF_X never existed either, so can be omitted from the IANA registry. But given the widespread deployment of clang's use, and the WG charter statement: > The BPF working group is initially tasked with documenting the existing > state of the BPF ecosystem I could see a potential argument to list it as reserved or something. Today, the document doesn't reserve it, so it's open for future use for any purpose. I just wanted to verify that the WG is ok with not listing it in the IANA registry, given the above information. 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[67.170.74.237]) by smtp.gmail.com with ESMTPSA id m1-20020a62f201000000b006ddc03c425bsm8004664pfh.180.2024.01.30.09.27.37 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Jan 2024 09:27:38 -0800 (PST) X-Google-Original-From: To: "'bpf'" , Date: Tue, 30 Jan 2024 09:27:36 -0800 Message-ID: <076001da53a1$9ebfa210$dc3ee630$@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mailer: Microsoft Outlook 16.0 Content-Language: en-us Thread-Index: AdpTn/i/+Jdzpl/jQ0iLyOHFFXfaaQ== Archived-At: Subject: [Bpf] ISA: BPF_CALL | BPF_X X-BeenThere: bpf@ietf.org X-Mailman-Version: 2.1.39 Precedence: list List-Archive: List-Post: List-Help: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: bpf-bounces@ietf.org Sender: "Bpf" X-Original-From: dthaler1968@googlemail.com From: dthaler1968=40googlemail.com@dmarc.ietf.org Message-ID: <20240130172736.J-oEDE-ufgw3eMSOu6WIrMl2oIxtD7fWYZfTna9rE_k@z> clang generates BPF code with opcode 0x8d (BPF_CALL | BPF_X, which it calls "callx"), when compiling with -O0 or -O1. Of course -O2 is recommended, but if anyone later defines opcode 0x8d for anything other than what clang means by it, it could cause problems. On the BPF_MSH thread at https://mailarchive.ietf.org/arch/msg/bpf/ogmS9qFhdBCxC4VrOWL7nzjSiXU/ Alexei wrote regarding BPF_ABS and BPF_IND: > DW never existed in classic bpf, so abs/ind never had DW flavor. > If some assembler/compiler decided to "support" them it's on them. > The standard must not list such things as deprecated. They never existed. Technically BPF_CALL | BPF_X never existed either, so can be omitted from the IANA registry. But given the widespread deployment of clang's use, and the WG charter statement: > The BPF working group is initially tasked with documenting the existing > state of the BPF ecosystem I could see a potential argument to list it as reserved or something. Today, the document doesn't reserve it, so it's open for future use for any purpose. I just wanted to verify that the WG is ok with not listing it in the IANA registry, given the above information. Dave -- Bpf mailing list Bpf@ietf.org https://www.ietf.org/mailman/listinfo/bpf