From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1191EC49EA3 for ; Mon, 28 Jun 2021 10:15:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDD2061C6B for ; Mon, 28 Jun 2021 10:15:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232490AbhF1KRc (ORCPT ); Mon, 28 Jun 2021 06:17:32 -0400 Received: from mout.kundenserver.de ([212.227.126.135]:33075 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231935AbhF1KRa (ORCPT ); Mon, 28 Jun 2021 06:17:30 -0400 Received: from [192.168.1.155] ([77.9.21.236]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.167]) with ESMTPSA (Nemesis) id 1Mq33i-1lTPOc2NxS-00nDbm; Mon, 28 Jun 2021 12:14:08 +0200 Subject: Re: Candidate Linux ABI for Intel AMX and hypothetical new related features To: Len Brown , Florian Weimer Cc: Peter Zijlstra , Dave Hansen via Libc-alpha , Dave Hansen , Rich Felker , Linux API , "Bae, Chang Seok" , X86 ML , LKML , Kyle Huey , Borislav Petkov , Andy Lutomirski , Thomas Gleixner , Keno Fischer , Arjan van de Ven , Willy Tarreau References: <874kf11yoz.ffs@nanos.tec.linutronix.de> <87k0ntazyn.ffs@nanos.tec.linutronix.de> <37833625-3e6b-5d93-cc4d-26164d06a0c6@intel.com> <9c8138eb-3956-e897-ed4e-426bf6663c11@intel.com> <87pmxk87th.fsf@oldenburg.str.redhat.com> <87wnqkzklg.fsf@oldenburg.str.redhat.com> From: "Enrico Weigelt, metux IT consult" Message-ID: <93e3b500-5992-a674-18e6-445d1db7b1f0@metux.net> Date: Mon, 28 Jun 2021 12:14:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: tl Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:lSyi4PgVQ1Q3XMSWurC8SV8Bg+7YTr6EDcg0xFwZhAa7CdyqBwo y2/PQTszne3zHE2CsHWbDrsqI1aT0Fw+n02sncfcu7QcpMZEty6ObhDerSaUl0s9CfeDbEW J2Bc+/nkZppt5TRvJoWV34h+G8u5LaqhHPfRNRzz2bOHkBKsxApDfFYKNkE0YoY/tRdKYbV 1Bg7WvHflG+7NRsPIiLEQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:g8YuvF7/MfU=:oBD29W2LKejICBROVCUpSA zT5DGff/UY7BI0cMzJmmJP24/uK3IfbR5+WZcqyOE+1SzEs48igl1vOzV78iqfe5pROsVrCTb j6TfKvTeZJ+UY8fHM4x2USvej2b449ydTYG1/TAu1uEgBLINXfla7hDQfeZh6CTuQhObNUyWE P/p6kobIV17khYQcJOHrk1ZDl5J1WmPwJFyB38AbfoSBV0JtLyuik7Vy8gRDDNhdNgK/Mj6s1 /G/ySKHQyVfeq8P77klUuIbY3PkxmUqkeHxXtDsVKEvQD3jdtiL2OLrLhiUJhTka7cadkvRb5 kuzoKaHgc8Fy+7u8klD2h+oG0X4FAfEsKS94cdfKSZ00xUvGFK5tpmAs/l/Mf1s+QL64daG0Y Ei6+vAoZlmcLH5bNg6k5rO4ZsUJHAlfbr+Ip/4w0gJyJChAoBybjtVcaSUAW4cJ+giK0CRc4Z ub49WhLJ4YbDE6XtcmdKZhpq/NZ1k/TWlaEQLo2Ur8/v12gy4EcrvxaAizThD0tvBcm4ZKgAU J366UcY8EfYz9wf+mQr1ok= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.06.21 01:11, Len Brown wrote: >> x86 CPU features detection for applications (and AMX) >> > > FWIW, I didn't receive it, because you excluded > > linux-kernel@vger.kernel.org me neither :( Maybe just repost it to LKML ? You mention the interface *was* designed with cpu features remaining constant over a process' lifetime. Between the line I'm reading that this might not be the case anymore. How could that happen ? Process migration on a different CPU (or perhaps on a different host) ? This is gonna be tricky, because this somehow needs to be synchronized with the application (even if we check the bits before calling some cpu-specific opcode, which also has some performance cost), there's still some window where the application might not yet recognize the change. So either we need some explicit migration points (where app tells, please let me finish this func first) or transparent emulation. Damn, how could the cpu designers come up with such weird concepts in the first place ? :o --mtx -- --- Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren GPG/PGP-Schlüssel zu. --- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287