From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shannon Zhao Subject: Re: [Qemu-devel] [PATCH v2] arm: change vendor ID for virtio-mmio Date: Thu, 30 Jul 2015 17:21:51 +0800 Message-ID: <55B9ECAF.9030703@huawei.com> References: <1438196676-30255-1-git-send-email-mst@redhat.com> <55B97C88.6010004@linaro.org> <20150730105923-mutt-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150730105923-mutt-send-email-mst@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" , Shannon Zhao Cc: Peter Maydell , Graeme Gregory , lkml - Kernel Mailing List , qemu-devel@nongnu.org, "virtualization@lists.linux-foundation.org" , Igor Mammedov List-Id: virtualization@lists.linuxfoundation.org On 2015/7/30 16:04, Michael S. Tsirkin wrote: > On Thu, Jul 30, 2015 at 09:23:20AM +0800, Shannon Zhao wrote: >> >> >> On 2015/7/30 3:16, Michael S. Tsirkin wrote: >>> ACPI spec 5.0 allows the use of PCI vendor IDs. >>> >> But virtio-mmio is not a PCI device, it's a platform device. > > Yes. ACPI spec 5.0 says: > > A valid PNP ID must be of the form "AAA####" where A is an uppercase > letter and # is a hex digit. A valid ACPI ID must be of the form > "NNNN####" where N is an uppercase letter or a digit ('0'-'9') and # is > a hex digit. This specification reserves the string "ACPI" for use only > with devices defined herein. > > It further reserves all strings representing 4 HEX digits for > exclusive use with PCI-assigned Vendor IDs. > > The second paragraph means if PCI SIG assigned you an ID, you > can use that without need to register it with ASWG. > > >> Why do we drop the previous way using "QEMUXXXX"? Something I missed? > > So that guests that bind to this interface will work fine with non QEMU > implementations of virtio-mmio. > I think kernel driver supports multiple IDs. If they don't want to "QEMUXXXX" as ACPI ID, it's free to add a new one like below. +static const struct acpi_device_id virtio_mmio_acpi_match[] = { + { "QEMU0005", }, + { "1AF4103F", }, + { } +}; +MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match); > It's just playing nice with others. > > We could have done something similar to pvpanic as well, except we > didn't and guests using the QEMU prefix have been released, > so we have to keep using that. > >>> Since we have one for virtio, it seems neater to use that >>> rather than LNRO. For the device ID, use 103F which is a legacy ID that >>> isn't used in virtio PCI spec - seems to make sense since virtio-mmio is >>> a legacy device but we don't know the correct device type. >>> >>> Guests should probably match everything in the range 1000-103F >>> (just like legacy pci drivers do) which will allow us to pass in the >>> actual ID in the future if we want to. >>> >>> Signed-off-by: Michael S. Tsirkin >>> --- >>> hw/arm/virt-acpi-build.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c >>> index f365140..dea61ba 100644 >>> --- a/hw/arm/virt-acpi-build.c >>> +++ b/hw/arm/virt-acpi-build.c >>> @@ -145,7 +145,7 @@ static void acpi_dsdt_add_virtio(Aml *scope, >>> >>> for (i = 0; i < num; i++) { >>> Aml *dev = aml_device("VR%02u", i); >>> - aml_append(dev, aml_name_decl("_HID", aml_string("LNRO0005"))); >>> + aml_append(dev, aml_name_decl("_HID", aml_string("1AF4103F"))); >>> aml_append(dev, aml_name_decl("_UID", aml_int(i))); >>> >>> Aml *crs = aml_resource_template(); >>> >> >> -- >> Shannon > > . > -- Shannon