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 lists.gnu.org (lists.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 89A9DC25B74 for ; Mon, 27 May 2024 07:37:37 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sBUv7-0003kS-0L; Mon, 27 May 2024 03:37:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBUui-0003WN-Oo; Mon, 27 May 2024 03:37:00 -0400 Received: from mail.ozlabs.org ([2404:9400:2221:ea00::3]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBUuV-0000I2-C0; Mon, 27 May 2024 03:37:00 -0400 Received: from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4VnnXB0V9Zz4x0y; Mon, 27 May 2024 17:36:42 +1000 (AEST) Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4VnnX71vDBz4x0K; Mon, 27 May 2024 17:36:38 +1000 (AEST) Message-ID: <6ef44e57-14b4-4498-b51b-7c486582c5ca@kaod.org> Date: Mon, 27 May 2024 09:36:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 00/10] ppc/pnv: Better big-core model, lpar-per-core, PC unit To: Nicholas Piggin , qemu-ppc@nongnu.org Cc: Caleb Schlossin , =?UTF-8?B?RnLDqWTDqXJpYyBCYXJyYXQ=?= , Daniel Henrique Barboza , qemu-devel@nongnu.org References: <20240526122612.473476-1-npiggin@gmail.com> <66c95ef6-8f94-4661-bc4c-8f5f7abcce1f@kaod.org> Content-Language: en-US, fr From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2404:9400:2221:ea00::3; envelope-from=SRS0=e5bn=M6=kaod.org=clg@ozlabs.org; helo=mail.ozlabs.org X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 5/27/24 09:32, Nicholas Piggin wrote: > On Mon May 27, 2024 at 4:25 PM AEST, Cédric Le Goater wrote: >> On 5/26/24 14:26, Nicholas Piggin wrote: >>> Primary motivation for this series is to improve big-core support. >>> Other things like SPR indirect, timebase state, PC xscom, are required >>> for minimal big core support. >>> >>> I'm still not 100% happy with the big-core topology model after this. >>> Maybe one day we add pnv big core and pnv small core structures. But >> >> I haven't look at the proposal yet, but indeed, we could introduce >> a new TYPE_PNV_CORE type for big cores only. > > Yeah. It's still tricky because big-core structure contains the CPUs > if you are running in small core mode. So it would really have to be > a PnvCPUCore and PnvPervasiveCore or something, where the former is > either SMT4 and 1:1 with the latter or SMT8 and 1:2 depending on mode. > > And some of the "CPU" type operations in big core mode still need to > operate on the small core. > > For now, the accessors and helpers seem to be not too bad. > >>> nothing is completely clean because big core mode still has certain >>> small core restrictions. I think for now we take a bit of mostly >>> abstracted ugliness in TCG code for the benefit of not spreading >>> hacks through pervasive (xscom) core addressing. >>> >>> After this series, power9 and power10 get through skiboot/Linux boot >> s >> >> Have you tried SMT8 on powernv8 ? I remember seeing a hang if I am correct. >> I don't think POWER8 deserves much attention anymore, we could deprecate >> POWER8E and POWER8NVL. However, we should at least report an error if we >> know a setup is broken. > > Yeah it does have some problem. Maybe should just disable SMT unless > someone finds time to work it out. The new _init routines would be a good place to do that. Thanks, C. > > Thanks, > Nick