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 ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (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 0C282C77B6E for ; Wed, 12 Apr 2023 05:15:14 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 4EE9F2B022 for ; Wed, 12 Apr 2023 05:15:13 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 3A156986520 for ; Wed, 12 Apr 2023 05:15:13 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 28A45986509; Wed, 12 Apr 2023 05:15:13 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 1504598650F for ; Wed, 12 Apr 2023 05:15:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: KFfuBfn6OM2FRWAL7BCEGQ-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681276510; x=1683868510; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=lr9nNQAT7/w/nt0aGjl9dF4DjMz/dSrtMPqZ/WEc7/E=; b=Uj66uRAWrGCcrype3V5Z7M1wxl7mGhcXM2BTgD0o4yQzxpaIKIEtQIVCKMCFCWJWBe QhpLaXke03fKJ4z3/pkIFd9pnebHpjXui9tN4w7r9Di6Imx0FSxloldpOpRgv9uJtOx7 JJs6aPHd8eqkJSfFOcQo9toLMaB2y2x1BgUvV0cr0m+PonOkJIPOz9jzP7hBf0/40ELN PlwhsAs9f3fCAMiJfXtcb/ReHVdAh/hHjkvOGwkv/eg/QGhkg4L7sCgwJ5caYkCmTmx9 yySgi5pR8UfmxpCGK+tc8DctHn9PmTYwGBw2TkJv7lB5iE/dLmOmaKroFd9/9EEQzZ9b RhCw== X-Gm-Message-State: AAQBX9eJ0X72bFyt3KLJD0bhL/RT4bbjTxCLOIvnzMBOMllbxYq3xTOg zlFxsIWHAIBMr3WXK+vCpnQ23RZel/lD3Pogb6jFJ/KF1SqTRJyssYVtiCyrHgNjFnk+Ymv3vq/ ke41ZFuImi97j3C2XrmZ7lNXaSYFZSweNEkm2G4o7A+TL X-Received: by 2002:a05:6870:d0c8:b0:17e:e007:7098 with SMTP id k8-20020a056870d0c800b0017ee0077098mr6295814oaa.9.1681276510611; Tue, 11 Apr 2023 22:15:10 -0700 (PDT) X-Google-Smtp-Source: AKy350ZjvhXPsy/QSUdPxn4jBFtdFGn1JAD8PAZmc6b9ji7wI7McadUhOosUhFploM6rubIv2kQntMFm6OPgTYAmAok= X-Received: by 2002:a05:6870:d0c8:b0:17e:e007:7098 with SMTP id k8-20020a056870d0c800b0017ee0077098mr6295809oaa.9.1681276510387; Tue, 11 Apr 2023 22:15:10 -0700 (PDT) MIME-Version: 1.0 References: <20230410020906-mutt-send-email-mst@kernel.org> <20230410023715-mutt-send-email-mst@kernel.org> <20230410060417-mutt-send-email-mst@kernel.org> <20230411030056-mutt-send-email-mst@kernel.org> <20230411063945-mutt-send-email-mst@kernel.org> <20230412000802-mutt-send-email-mst@kernel.org> In-Reply-To: From: Jason Wang Date: Wed, 12 Apr 2023 13:14:59 +0800 Message-ID: To: Parav Pandit Cc: "Michael S. Tsirkin" , "virtio-dev@lists.oasis-open.org" , "cohuck@redhat.com" , "virtio-comment@lists.oasis-open.org" , Shahaf Shuler , Satananda Burla , Maxime Coquelin , Yan Vugenfirer X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: [virtio-dev] Re: [virtio-comment] Re: [PATCH 09/11] transport-pci: Describe PCI MMR dev config registers On Wed, Apr 12, 2023 at 1:01=E2=80=AFPM Parav Pandit wro= te: > > > > > From: Jason Wang > > Sent: Wednesday, April 12, 2023 12:51 AM > > > > Yes, but this proposal will drag us back to legacy, isn't it? > No. This proposal supports the legacy transitional pci device. > > > Or if it is used only in > > the vitalization environment, what's the advantages of doing it over si= mply > > mediating on top of modern device? > > > Because the spec for modern device do not allow it. Discussed in these th= reads. Can you please tell me which part of the spec disallows it? There's a long discussion in the virtualization-list a few months ago about mediating legacy devices on top of modern. We don't see any blocker do you? > > > 1) legacy MMIO bar: spec changes, hypervisor mediation > > 2) modern device: no spec changes, hypervisor mediation > > > This question repeats the same discussion occurred in this patch series. > You might want to refer it again to avoid repeating all over again. No, I think you miss the point that modern devices could be used for mediating legacy devices. > > > 1) it's better not invent any of new facilities for legacy > > 2) if legacy is insisted, allow MMIO BAR0 is much simpler and better > You have missed few emails. :) > MMIO BAR is proposed here and it is not limited to BAR 0. In the context of mediation, why do you need that flexibility? > It is left for the device to either map something in existing BAR or use = BAR 0. > Because PCI has only 3 BARs. > A device may want to support legacy and non-legacy functionality both at = the same time. This is perfectly fine, this is how Qemu did: /* * virtio pci bar layout used by default. * subclasses can re-arrange things if needed. * * region 0 -- virtio legacy io bar * region 1 -- msi-x bar * region 2 -- virtio modern io bar (off by default) * region 4+5 -- virtio modern memory (64bit) bar * */ > So better not to hard wire for BAR 0. Using BAR0 doesn't prevent you from adding modern capabilities in BAR0, no? Thanks --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org