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[83.52.54.37]) by smtp.gmail.com with ESMTPSA id ov22sm75075ejb.70.2020.03.19.02.42.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Mar 2020 02:42:55 -0700 (PDT) Subject: Re: [PATCH-for-5.0 1/2] hw/acpi/piix4: Add 'system-hotplug-support' property To: Paolo Bonzini , qemu-devel@nongnu.org References: <20200318221531.22910-1-philmd@redhat.com> <20200318221531.22910-2-philmd@redhat.com> <3ac0d8f1-15d8-51d3-b40e-8975ec1353ad@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <1b61a51a-0419-1bd3-2728-e5c11606f99e@redhat.com> Date: Thu, 19 Mar 2020 10:42:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <3ac0d8f1-15d8-51d3-b40e-8975ec1353ad@redhat.com> Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 63.128.21.74 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , Marcelo Tosatti , Aleksandar Markovic , =?UTF-8?Q?Herv=c3=a9_Poussineau?= , Igor Mammedov , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/19/20 10:36 AM, Paolo Bonzini wrote: > On 18/03/20 23:15, Philippe Mathieu-Daud=C3=A9 wrote: >> The I/O ranges registered by the piix4_acpi_system_hot_add_init() >> function are not documented in the PIIX4 datasheet. >> This appears to be a PC-only feature added in commit 5e3cb5347e >> ("initialize hot add system / acpi gpe") which was then moved >> to the PIIX4 device model in commit 9d5e77a22f ("make >> qemu_system_device_hot_add piix independent") >> Add a property (default enabled, to not modify the current >> behavior) to allow machines wanting to model a simple PIIX4 >> to disable this feature. >=20 > Yes, all hotplug stuff (PCI/memory/CPU) are custom additions by QEMU. >=20 >> + DEFINE_PROP_BOOL("system-hotplug-support", PIIX4PMState, >> + use_acpi_system_hotplug, true), >=20 > Why not cpu-hotplug-support? Because I have no idea what this code is about, and it seems more than=20 cpu (pci, memory): static void piix4_acpi_system_hot_add_init(MemoryRegion *parent, PCIBus *bus, PIIX4PMState *s) { memory_region_init_io(&s->io_gpe, OBJECT(s), &piix4_gpe_ops, s, "acpi-gpe0", GPE_LEN); memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe); acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent, s->use_acpi_pci_hotplug); s->cpu_hotplug_legacy =3D true; object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy", piix4_get_cpu_hotplug_legacy, piix4_set_cpu_hotplug_legacy, NULL); legacy_acpi_cpu_hotplug_init(parent, OBJECT(s), &s->gpe_cpu, PIIX4_CPU_HOTPLUG_IO_BASE); if (s->acpi_memory_hotplug.is_enabled) { acpi_memory_hotplug_init(parent, OBJECT(s),=20 &s->acpi_memory_hotplug, ACPI_MEMORY_HOTPLUG_BASE); } }