From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C38B619BA9 for ; Tue, 11 Jul 2023 14:04:18 +0000 (UTC) Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:470:142:3::10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7C82E69 for ; Tue, 11 Jul 2023 07:04:16 -0700 (PDT) Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qJDyQ-00006L-GR; Tue, 11 Jul 2023 10:04:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=MIME-Version:Date:References:In-Reply-To:Subject:To: From; bh=NpaSxipqmX9poXsWhpR4q+yVnkTQK1VtwmJHQsc4V+4=; b=kDM2+rc6xNCwgr3roFyT PMNMjRFLZmusqaYHjXxSGSz++Umfqnx7TkydDsvYFqd+uoEJn0qxk1al/MDPg5+SOBlua9iU9rqs4 WYW04kpTVkdQy7afgsuwyF4ofHnT3hFvF1/FClLSQ6eCipy0Lm8MmubqxeckAFVuAoVWBGjqnoAn7 4L836Xd8jtNP7HeOMhL+A5xyN4LEXZUm49z9w1auWcKAX7Vwq57AZKreSw2UxAMC5y0OguEFgehxd tgMtDQo8IVZZdFKQYKXc8FuH5IJXLOu0WGEL/TdeMsKS2K2NJT29+AB43TgXzcuCOnzDA/+Fn9aF1 wHKsaiwD0Dh6fg==; Received: from [141.143.193.69] (helo=termi) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qJDyQ-0000RG-4q; Tue, 11 Jul 2023 10:04:14 -0400 From: "Jose E. Marchesi" To: Alexei Starovoitov Cc: Will Hawkins , bpf , bpf@ietf.org Subject: Re: [Bpf] [PATCH 1/1] bpf, docs: Specify twos complement as format for signed integers In-Reply-To: (Alexei Starovoitov's message of "Mon, 10 Jul 2023 20:00:31 -0700") References: <20230710215819.723550-1-hawkinsw@obs.cr> <20230710215819.723550-2-hawkinsw@obs.cr> Date: Tue, 11 Jul 2023 16:04:11 +0200 Message-ID: <871qhe7des.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net > On Mon, Jul 10, 2023 at 2:58=E2=80=AFPM Will Hawkins wr= ote: >> >> In the documentation of the eBPF ISA it is unspecified how integers are >> represented. Specify that twos complement is used. >> >> Signed-off-by: Will Hawkins >> --- >> Documentation/bpf/instruction-set.rst | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/Documentation/bpf/instruction-set.rst b/Documentation/bpf/i= nstruction-set.rst >> index 751e657973f0..63dfcba5eb9a 100644 >> --- a/Documentation/bpf/instruction-set.rst >> +++ b/Documentation/bpf/instruction-set.rst >> @@ -173,6 +173,11 @@ BPF_ARSH 0xc0 sign extending dst >>=3D (src & ma= sk) >> BPF_END 0xd0 byte swap operations (see `Byte swap instructions`_ be= low) >> =3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >> >> +eBPF supports 32- and 64-bit signed and unsigned integers. It does >> +not support floating-point data types. All signed integers are represen= ted in >> +twos-complement format where the sign bit is stored in the most-signifi= cant >> +bit. > > Could you point to another ISA document (like x86, arm, ...) that > talks about signed and unsigned integers? AFAIK the only signedness encoding aspect that is always found in ISA specifications and should be specified is how numerical immediates are encoded in stored instructions. But that has nothing to do with "data types". 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Marchesi" To: Alexei Starovoitov Cc: Will Hawkins , bpf , bpf@ietf.org In-Reply-To: (Alexei Starovoitov's message of "Mon, 10 Jul 2023 20:00:31 -0700") References: <20230710215819.723550-1-hawkinsw@obs.cr> <20230710215819.723550-2-hawkinsw@obs.cr> Date: Tue, 11 Jul 2023 16:04:11 +0200 Message-ID: <871qhe7des.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Archived-At: Subject: Re: [Bpf] [PATCH 1/1] bpf, docs: Specify twos complement as format for signed integers X-BeenThere: bpf@ietf.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: Discussion of BPF/eBPF standardization efforts within the IETF List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: bpf-bounces@ietf.org Sender: "Bpf" X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Message-ID: <20230711140411.S25BdFwF2w1A2SYlG-stWL6nnMJ6QeQE825cCMHZL40@z> Cj4gT24gTW9uLCBKdWwgMTAsIDIwMjMgYXQgMjo1OOKAr1BNIFdpbGwgSGF3a2lucyA8aGF3a2lu c3dAb2JzLmNyPiB3cm90ZToKPj4KPj4gSW4gdGhlIGRvY3VtZW50YXRpb24gb2YgdGhlIGVCUEYg SVNBIGl0IGlzIHVuc3BlY2lmaWVkIGhvdyBpbnRlZ2VycyBhcmUKPj4gcmVwcmVzZW50ZWQuIFNw ZWNpZnkgdGhhdCB0d29zIGNvbXBsZW1lbnQgaXMgdXNlZC4KPj4KPj4gU2lnbmVkLW9mZi1ieTog V2lsbCBIYXdraW5zIDxoYXdraW5zd0BvYnMuY3I+Cj4+IC0tLQo+PiAgRG9jdW1lbnRhdGlvbi9i cGYvaW5zdHJ1Y3Rpb24tc2V0LnJzdCB8IDUgKysrKysKPj4gIDEgZmlsZSBjaGFuZ2VkLCA1IGlu c2VydGlvbnMoKykKPj4KPj4gZGlmZiAtLWdpdCBhL0RvY3VtZW50YXRpb24vYnBmL2luc3RydWN0 aW9uLXNldC5yc3QgYi9Eb2N1bWVudGF0aW9uL2JwZi9pbnN0cnVjdGlvbi1zZXQucnN0Cj4+IGlu ZGV4IDc1MWU2NTc5NzNmMC4uNjNkZmNiYTVlYjlhIDEwMDY0NAo+PiAtLS0gYS9Eb2N1bWVudGF0 aW9uL2JwZi9pbnN0cnVjdGlvbi1zZXQucnN0Cj4+ICsrKyBiL0RvY3VtZW50YXRpb24vYnBmL2lu c3RydWN0aW9uLXNldC5yc3QKPj4gQEAgLTE3Myw2ICsxNzMsMTEgQEAgQlBGX0FSU0ggIDB4YzAg ICBzaWduIGV4dGVuZGluZyBkc3QgPj49IChzcmMgJiBtYXNrKQo+PiAgQlBGX0VORCAgIDB4ZDAg ICBieXRlIHN3YXAgb3BlcmF0aW9ucyAoc2VlIGBCeXRlIHN3YXAgaW5zdHJ1Y3Rpb25zYF8gYmVs b3cpCj4+ICA9PT09PT09PSAgPT09PT0gID09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT0KPj4KPj4gK2VCUEYgc3VwcG9ydHMgMzItIGFuZCA2 NC1iaXQgc2lnbmVkIGFuZCB1bnNpZ25lZCBpbnRlZ2Vycy4gSXQgZG9lcwo+PiArbm90IHN1cHBv cnQgZmxvYXRpbmctcG9pbnQgZGF0YSB0eXBlcy4gQWxsIHNpZ25lZCBpbnRlZ2VycyBhcmUgcmVw cmVzZW50ZWQgaW4KPj4gK3R3b3MtY29tcGxlbWVudCBmb3JtYXQgd2hlcmUgdGhlIHNpZ24gYml0 IGlzIHN0b3JlZCBpbiB0aGUgbW9zdC1zaWduaWZpY2FudAo+PiArYml0Lgo+Cj4gQ291bGQgeW91 IHBvaW50IHRvIGFub3RoZXIgSVNBIGRvY3VtZW50IChsaWtlIHg4NiwgYXJtLCAuLi4pIHRoYXQK PiB0YWxrcyBhYm91dCBzaWduZWQgYW5kIHVuc2lnbmVkIGludGVnZXJzPwoKQUZBSUsgdGhlIG9u bHkgc2lnbmVkbmVzcyBlbmNvZGluZyBhc3BlY3QgdGhhdCBpcyBhbHdheXMgZm91bmQgaW4gSVNB CnNwZWNpZmljYXRpb25zIGFuZCBzaG91bGQgYmUgc3BlY2lmaWVkIGlzIGhvdyBudW1lcmljYWwg aW1tZWRpYXRlcyBhcmUKZW5jb2RlZCBpbiBzdG9yZWQgaW5zdHJ1Y3Rpb25zLgoKQnV0IHRoYXQg aGFzIG5vdGhpbmcgdG8gZG8gd2l0aCAiZGF0YSB0eXBlcyIuCgotLSAKQnBmIG1haWxpbmcgbGlz dApCcGZAaWV0Zi5vcmcKaHR0cHM6Ly93d3cuaWV0Zi5vcmcvbWFpbG1hbi9saXN0aW5mby9icGYK