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 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A2DCCCCA462 for ; Fri, 16 Oct 2026 10:26:43 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xHf8q-0005LQ-C8; Fri, 16 Oct 2026 06:26:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xHf8o-0005L3-LD for qemu-riscv@nongnu.org; Fri, 16 Oct 2026 06:26:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xHf8m-0003i9-Hg for qemu-riscv@nongnu.org; Fri, 16 Oct 2026 06:26:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1792146379; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=JtV4l8kuhdz5qUfm3CwSyjyb9zLGcWsb18783vWGy04=; b=FhXzXbkDSK1exHGDNampADWJ2j2DDECukCgYGMteE//leH6riJ1Hyb7iaoC7d4zG0BB4bX TpUNR/CVCMZM1aIzGqfIau7dPTgdKzvk7pJjKUD/pDred3fjsvH9f1nyG2HGzQ2SR9NpFg 7XaA+cuWocNxY2YlOB02iaxQrCUd4ug= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-135-oV9ysyIJOcOqESzJsv1sgg-1; Fri, 16 Oct 2026 10:26:15 +0000 X-MC-Unique: oV9ysyIJOcOqESzJsv1sgg-1 X-Mimecast-MFC-AGG-ID: oV9ysyIJOcOqESzJsv1sgg_1792146373 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AB917195422B; Fri, 16 Oct 2026 10:26:12 +0000 (UTC) Received: from redhat.com (headnet03.pony-001.prod.iad2.dc.redhat.com [10.2.32.114]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E80651800765; Fri, 16 Oct 2026 10:26:06 +0000 (UTC) Date: Fri, 16 Oct 2026 11:26:03 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Daniel Henrique Barboza Cc: Portia Stephens , qemu-devel@nongnu.org, Nicholas Piggin , Palmer Dabbelt , Chao Liu , Alistair Francis , qemu-riscv@nongnu.org, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Paolo Bonzini , Joel Stanley , Liu Zhiwei , Alex =?utf-8?Q?Benn=C3=A9e?= , Pierrick Bouvier , Weiwei Li , Anirudh Srinivasan , Richard Henderson , Zhao Liu , Michael Ellerman Subject: Re: [PATCH 07/12] machine: Support extra board CPUs outside -smp Message-ID: References: <20261015031804.2406055-1-portias@oss.tenstorrent.com> <20261015031804.2406055-8-portias@oss.tenstorrent.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.4.2 (2026-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: IOWIZNnsu4PiH3z3nSl2OBP-1PXN5KRQA4OGcRNDl40_1792146373 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 10 X-Spam_score: 1.0 X-Spam_bar: + X-Spam_report: (1.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.24, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-riscv@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-riscv-bounces+qemu-riscv=archiver.kernel.org@nongnu.org Sender: qemu-riscv-bounces+qemu-riscv=archiver.kernel.org@nongnu.org On Thu, Oct 15, 2026 at 05:31:33PM -0300, Daniel Henrique Barboza wrote: > Phil, Pierrick, > > This patch seems to dwell around your turf. Did you think about how to > instantiate different CPUs that might have different SMP topologies in > the context of single binary/split accel work? IMHO the -smp argument as it exists today is essentially unfixable for the general case and will ultimately need to be declared legacy / for simplistic usage only. Trying to paper over the limitations of -smp with special cases like "extra cpus" is unlikely to deliver attractive solutions long term. The eventual emulation of heterogeneous CPUS in the single binary work will bring this to a head, but it already causes problems today with our per-target binaries because even individual the real world CPUs we want to be able to model are not symmetric. As a historical reference, a while back, Zhao had an RFC that proposed we use '-device' to define each topology level discretely, which would allow for arbitrary asymmetric topologies: https://lists.gnu.org/archive/html/qemu-devel/2024-09/msg03727.html With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|