From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 04082349AE1 for ; Wed, 17 Dec 2025 14:00:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765980040; cv=none; b=IvoVLKeeDmbsEaoKobC+uf0pUXYXHpzyFBJIgqn7Tb5nMMHCKbFvGVhfn78iESL8VTpR0nsJQFvt8C4xhUjxdMEyxiNVYwebsIP2w88Oqhe0WYikcb3CKgAU1mbDTt4WvoNpXdFRdc0o7+dzcbC08HrNK+9hdYyvU37gjvGJIDc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765980040; c=relaxed/simple; bh=cID+ZVg6VpXXH5zpDT6fnjB/6M2CKZw8A847+o/J+ng=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=niqchPABv6SU49ZH1g0VDDEIVVXOCOML9b+6lDdLQN/QO1/AND+s87goAHpMufNmxRVc4LwTGoqD3+OeJ50FAxisbcIb7hAnH2NdGCrkwgwGsyLvXL3ZnGB4+pJBwAZkuF3tN2FrzCSGa/VwRbtOerwTGUyGEGn/PGEfIMcsFGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=C5+/DREw; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=L6XNEMhE; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C5+/DREw"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="L6XNEMhE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1765980037; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HbthGM/G+GWpXtODayU7RTgZ2Jepun9Dt1c05gz+DX8=; b=C5+/DREwHBVfoLmVKc2LutKjYSb5OqzbVFwJ7oszdJwqIoADCyPFg2Q12tZzwMHpxhj7j1 rwN6VoErpKRI/R4oiYzxwp3n8ld2JKRtxTKMop+eHNzGhZXGVdgofIAk+dtPaZjQ5KsSeJ +lDNnvbw64kSFaM3fe0XS1yqQZcgkzM= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-643-hCytScPiOpiq-23cn3VFMA-1; Wed, 17 Dec 2025 09:00:36 -0500 X-MC-Unique: hCytScPiOpiq-23cn3VFMA-1 X-Mimecast-MFC-AGG-ID: hCytScPiOpiq-23cn3VFMA_1765980035 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-47918084ac1so53700775e9.2 for ; Wed, 17 Dec 2025 06:00:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1765980035; x=1766584835; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=HbthGM/G+GWpXtODayU7RTgZ2Jepun9Dt1c05gz+DX8=; b=L6XNEMhEE40T7TfCeDdKHoBGdRbXUfH5yv+kK6jiynSWeY6P/B0uwZbaoq/qMvtWeg ReMkbzVTo02vmWbekkKD9WI/YDttWaKM7aGRTJd3+7lAOuyxdGDTbtOdsSBpGYlZ9hd/ r+UiLeNpBz1i1VD8XKO1rOQH+NQDu0lS7Vld4qE+LLAqXJ7jjbqXUj2/ICJ4wCRN4ieq IojuA9M3+lJTDNLTZxFjVRdNmj7Htyp5uEasAxNSWBHefzE/LZ2dD9Z5awfL51jVjeEn FrU9Njz0SYHOVt8rj0ggw6vv7yXSOKjBzYeJJTVhhNkfErDxB/ZLFkjHJwfZP7XHz2nC /VjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765980035; x=1766584835; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=HbthGM/G+GWpXtODayU7RTgZ2Jepun9Dt1c05gz+DX8=; b=mlSFq2Aiy8f73z3zmbgyAqFy1TPLBnBfDAa9xVmZkLhfgdsXL8DmQWqQRZMZYuXeNJ 8r9a7nFzc/qgQU70PfxmBziAOVRMMVObVsNMcUguQtwLzO0IzdufxXmTICmsl5DPIkJd 1EgViUI0iLgmcXqqbxGH380wV4kd5mz4BFgW1FQf1S2y8ya9MXqYPDpSzpYPRhDOgXAq ojOz47XEIHjAFWXi8B90ZU7q15spWCI6TuMJPArGvPdaMaMgUetWyrOtp8BPEV2WivYK AKJ06yZxBP/9urEzibZxeMOewaAIDV5Oh+G25Zl8SkDN96Ou2qzMDnPLHherhohiR+hZ jJfg== X-Forwarded-Encrypted: i=1; AJvYcCVI/pmuzr05SaUC7Bb+0olLHbxGS6Z9Vi8k6I0WALueqC740VyNG/ZbZ6V106ReXQf1tmU=@vger.kernel.org X-Gm-Message-State: AOJu0YzUqGsz/FqpPrsrCqVj1nSM+v3xtRbWL0wEcfe2mS36/L8Yw9bC vMps6b0rfs6XAx1d9MTCJsLz9uQNXY/Kf3txJcpc2gdgEybqo3gMnBoq8tBbOcMnqnDpPASamMP TVEUbeZ/sPXTFLKYpaUTF0qYrp2miGd+CBEnEYxhKAmbunOeflEO/fw== X-Gm-Gg: AY/fxX5p61LUSwFkeppQmzgWmWjkZlVI6XOy9lyIVCaZd9BVE8QtUYsqVMFNlt3Kfko NjroLcjsSi5bVGefTgQgXb5Ptpal1xr57PCR20I7tdH2x9c8jJV6vSLHXvdjcspvZG9OSbtUvYi kvvj4D2oXi1cimY5Sw7HcQI1ncVbnS88Y6ma17VCqbIC/iQ6NLkYkQEWExJ6Qjk2NsgQdFjUevv BGc2sRbRu34ukrSRAWO5HwUBJhAPUZb3tq5bD5+i8KgabXNweewJ08Ts+ClO7Ci7Xe2XW5Ntjfy AAHVpIvniqRyvWvrI4zi5BOQZm+jdASGhNYZy9LbIRtPliPNbfaUtaUEJh9/LynUETCJBw== X-Received: by 2002:a05:600c:870b:b0:477:214f:bd95 with SMTP id 5b1f17b1804b1-47a970ee01fmr121266415e9.23.1765980035277; Wed, 17 Dec 2025 06:00:35 -0800 (PST) X-Google-Smtp-Source: AGHT+IHF3Fr/Zcas6umUDcUr9uZT23jIj6/PQ2ws/ggCzapTqhVg7JQ7VBdYoNAD+a6a+0T+RRnEZw== X-Received: by 2002:a05:600c:870b:b0:477:214f:bd95 with SMTP id 5b1f17b1804b1-47a970ee01fmr121266215e9.23.1765980034769; Wed, 17 Dec 2025 06:00:34 -0800 (PST) Received: from imammedo ([213.175.46.86]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47bd932a3e5sm30087275e9.0.2025.12.17.06.00.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 06:00:34 -0800 (PST) Date: Wed, 17 Dec 2025 15:00:29 +0100 From: Igor Mammedov To: Zhao Liu Cc: Paolo Bonzini , "Michael S . Tsirkin" , Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= , Marcel Apfelbaum , Thomas Huth , qemu-devel@nongnu.org, devel@lists.libvirt.org, kvm@vger.kernel.org, qemu-riscv@nongnu.org, qemu-arm@nongnu.org, Richard Henderson , Sergio Lopez , Gerd Hoffmann , Peter Maydell , Laurent Vivier , Jiaxun Yang , Yi Liu , Eduardo Habkost , Alistair Francis , Daniel Henrique Barboza , Marcelo Tosatti , Weiwei Li , Amit Shah , Xiaoyao Li , Yanan Wang , Helge Deller , Palmer Dabbelt , "Daniel P . =?UTF-8?B?QmVycmFuZ8Op?=" , Ani Sinha , Fabiano Rosas , Liu Zhiwei , =?UTF-8?B?Q2zDqW1lbnQ=?= Mathieu--Drif , =?UTF-8?B?TWFyYy1BbmRyw6k=?= Lureau , Huacai Chen , Jason Wang , Mark Cave-Ayland , BALATON Zoltan , Peter Krempa , Jiri Denemark Subject: Re: [PATCH v5 06/28] docs/specs/acpi_cpu_hotplug: Remove legacy cpu hotplug descriptions Message-ID: <20251217150029.3a3bc19d@imammedo> In-Reply-To: <20251202162835.3227894-7-zhao1.liu@intel.com> References: <20251202162835.3227894-1-zhao1.liu@intel.com> <20251202162835.3227894-7-zhao1.liu@intel.com> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 3 Dec 2025 00:28:13 +0800 Zhao Liu wrote: > Legacy cpu hotplug has been removed totally and machines start with > modern cpu hotplug interface directly. > > Therefore, update the documentation to describe current QEMU cpu hotplug > logic. > > Signed-off-by: Zhao Liu Reviewed-by: Igor Mammedov > --- > Changes since v4: > * New patch. > --- > docs/specs/acpi_cpu_hotplug.rst | 28 +++------------------------- > 1 file changed, 3 insertions(+), 25 deletions(-) > > diff --git a/docs/specs/acpi_cpu_hotplug.rst b/docs/specs/acpi_cpu_hotplug.rst > index 351057c96761..f49678100044 100644 > --- a/docs/specs/acpi_cpu_hotplug.rst > +++ b/docs/specs/acpi_cpu_hotplug.rst > @@ -8,22 +8,6 @@ ACPI BIOS GPE.2 handler is dedicated for notifying OS about CPU hot-add > and hot-remove events. > > > -Legacy ACPI CPU hotplug interface registers > -------------------------------------------- > - > -CPU present bitmap for: > - > -- ICH9-LPC (IO port 0x0cd8-0xcf7, 1-byte access) > -- PIIX-PM (IO port 0xaf00-0xaf1f, 1-byte access) > -- One bit per CPU. Bit position reflects corresponding CPU APIC ID. Read-only. > -- The first DWORD in bitmap is used in write mode to switch from legacy > - to modern CPU hotplug interface, write 0 into it to do switch. > - > -QEMU sets corresponding CPU bit on hot-add event and issues SCI > -with GPE.2 event set. CPU present map is read by ACPI BIOS GPE.2 handler > -to notify OS about CPU hot-add events. CPU hot-remove isn't supported. > - > - > Modern ACPI CPU hotplug interface registers > ------------------------------------------- > > @@ -189,20 +173,14 @@ Typical usecases > (x86) Detecting and enabling modern CPU hotplug interface > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > -QEMU starts with legacy CPU hotplug interface enabled. Detecting and > -switching to modern interface is based on the 2 legacy CPU hotplug features: > - > -#. Writes into CPU bitmap are ignored. > -#. CPU bitmap always has bit #0 set, corresponding to boot CPU. > - > -Use following steps to detect and enable modern CPU hotplug interface: > +QEMU starts with modern CPU hotplug interface enabled. Use following steps to > +detect modern CPU hotplug interface: > > -#. Store 0x0 to the 'CPU selector' register, attempting to switch to modern mode > #. Store 0x0 to the 'CPU selector' register, to ensure valid selector value > #. Store 0x0 to the 'Command field' register > #. Read the 'Command data 2' register. > If read value is 0x0, the modern interface is enabled. > - Otherwise legacy or no CPU hotplug interface available > + Otherwise no CPU hotplug interface available > > Get a cpu with pending event > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^