Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215AbbG3PCm (ORCPT ); Thu, 30 Jul 2015 11:02:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60180 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752012AbbG3PCl (ORCPT ); Thu, 30 Jul 2015 11:02:41 -0400 Date: Thu, 30 Jul 2015 18:02:36 +0300 From: "Michael S. Tsirkin" To: Shannon Zhao Cc: Shannon Zhao , qemu-devel@nongnu.org, Peter Maydell , Graeme Gregory , lkml - Kernel Mailing List , "virtualization@lists.linux-foundation.org" , Igor Mammedov , Alex =?iso-8859-1?Q?Benn=E9e?= Subject: Re: [Qemu-devel] [PATCH v2] arm: change vendor ID for virtio-mmio Message-ID: <20150730180207-mutt-send-email-mst@redhat.com> References: <1438196676-30255-1-git-send-email-mst@redhat.com> <55B97C88.6010004@linaro.org> <20150730105923-mutt-send-email-mst@redhat.com> <55B9ECAF.9030703@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55B9ECAF.9030703@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3396 Lines: 93 On Thu, Jul 30, 2015 at 05:21:51PM +0800, Shannon Zhao wrote: > > > 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); Yes but that won't work with existing disto kernels. > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/