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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 51188C433ED for ; Fri, 23 Apr 2021 19:58:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E5C36144A for ; Fri, 23 Apr 2021 19:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243887AbhDWT6j (ORCPT ); Fri, 23 Apr 2021 15:58:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232645AbhDWT6h (ORCPT ); Fri, 23 Apr 2021 15:58:37 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFCF5C061574; Fri, 23 Apr 2021 12:57:59 -0700 (PDT) Received: from zn.tnic (p200300ec2f0cb1003e0d9ed13dff4615.dip0.t-ipconnect.de [IPv6:2003:ec:2f0c:b100:3e0d:9ed1:3dff:4615]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 70E671EC0249; Fri, 23 Apr 2021 21:57:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1619207876; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=wvsKEi1eJGHeLPZJEa6xjsiy+KUSZ+p+/AowYRFXmJo=; b=NAgX5GALzUPNTfLUFHa98J47MGRV4yTiiQNhL10loUF9WoVcrYAhVEv2tu2YyjJD2faiRP qctjdpxPjB3TTCnPyHb2w1QOpGC2jzJtrjaOhODIQhwDpS66zkFmVTWAxPsngtLDSL41zB u4Ja05+8K/mhHO7JeUHNF7vAiDozpw0= Date: Fri, 23 Apr 2021 21:57:54 +0200 From: Borislav Petkov To: Len Brown Cc: Willy Tarreau , Andy Lutomirski , Florian Weimer , "Bae, Chang Seok" , Dave Hansen , X86 ML , LKML , linux-abi@vger.kernel.org, "libc-alpha@sourceware.org" , Rich Felker , Kyle Huey , Keno Fischer Subject: Re: Candidate Linux ABI for Intel AMX and hypothetical new related features Message-ID: References: <20210415044258.GA6318@zn.tnic> <20210415052938.GA2325@1wt.eu> <20210415054713.GB6318@zn.tnic> <20210419141454.GE9093@zn.tnic> <20210419191539.GH9093@zn.tnic> <20210419215809.GJ9093@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 23, 2021 at 03:35:30PM -0400, Len Brown wrote: > Yes. If a library decides to execute AMX instructions on behalf > of a task, the kernel will allocate an 8KB context switch buffer > on behalf of that task. Again, the library should ask the kernel first whether it supports AMX. And the process should decide whether to use AMX - not the library on its own, on behalf of the process. > Granted, if you find a reason to dislike AMX, the mechanisms to disable > it today are on a system-wide basis, not on a process or task basis. Again, I don't dislike the feature. I don't want libraries jumping on new features without asking the process or the kernel first especially when those features have performance implications and need kernel support. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette