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 105F8C7EE24 for ; Mon, 5 Jun 2023 05:52:05 +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 361BDC6225 for ; Mon, 5 Jun 2023 05:52:05 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 2190D986423 for ; Mon, 5 Jun 2023 05:52:05 +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 07EAA98633F; Mon, 5 Jun 2023 05:52:05 +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 DFBD398634B for ; Mon, 5 Jun 2023 05:52:04 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: LIdEpDbcN9eISOLqET4GKg-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685944321; x=1688536321; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=kOyrVr3blhfvjoWSnvGMl4xI8Hxfh0XzRzn4ppUBkcE=; b=AJll3PJ0GPaVv7N2yix0vS1uZsiA/6keI68GsCJCNDftLINRrKEvsQuzO+uD6J5UhE lWT+kGMT0QLQBU/zlHPEutWmo58C2C1Py2uBJGZOJgWbLyNc4uUKHe/4FxUNvzdqnsME kNmihBLELMT0pj8kFFomZYnVNfqVd+pud925+TZUONjcI1yRflOAOWR7BQ3SpQLoMmGQ V934aJ1NA5Y2lTniP7ENQ/41ZorkmDNljrR/LQsygBd5LE24gsoJIX/HfVehEnN7lBW2 uG6LKyTcGakL9aYYKsgTgpT6mXdS0DXLTdWprbZfCtQiNbD/08WyEUQo7CYkAMabELRz oPxQ== X-Gm-Message-State: AC+VfDxy5GmuqO5DJi5I0WhsL9Ko6YyrpKM375Wz7BNwGwYF+McIAYo0 0J4mWAZQAQCNK/ECLKMg+f2onAJfZj9UymPokt2uiW71YB2wKjPSo4YDrsdI2UfjmLCwgdWTKEh I6xKvfBhuMbMyrFXL3VVwWMF5JHGQ X-Received: by 2002:a1c:7512:0:b0:3f6:af2:8471 with SMTP id o18-20020a1c7512000000b003f60af28471mr6778515wmc.26.1685944321633; Sun, 04 Jun 2023 22:52:01 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ7zN4A1bxTPjp1x8qVuWh70OP382MSsn9NUvbsW1o7CbreS/xxB40GMSRX2BY8jp7+F9OY9Aw== X-Received: by 2002:a1c:7512:0:b0:3f6:af2:8471 with SMTP id o18-20020a1c7512000000b003f60af28471mr6778503wmc.26.1685944321302; Sun, 04 Jun 2023 22:52:01 -0700 (PDT) Date: Mon, 5 Jun 2023 01:51:57 -0400 From: "Michael S. Tsirkin" To: Parav Pandit Cc: "virtio-dev@lists.oasis-open.org" , "cohuck@redhat.com" , "david.edmondson@oracle.com" , "sburla@marvell.com" , "jasowang@redhat.com" , Yishai Hadas , Maor Gottlieb , "virtio-comment@lists.oasis-open.org" , Shahaf Shuler Message-ID: <20230605014539-mutt-send-email-mst@kernel.org> References: <20230604092441-mutt-send-email-mst@kernel.org> <20230604094535-mutt-send-email-mst@kernel.org> <20230604101351-mutt-send-email-mst@kernel.org> <20230604105027-mutt-send-email-mst@kernel.org> <20230604174224-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [virtio-dev] Re: [PATCH v3 0/3] transport-pci: Introduce legacy registers access using AQ On Sun, Jun 04, 2023 at 11:40:54PM +0000, Parav Pandit wrote: > > > > From: Michael S. Tsirkin > > Sent: Sunday, June 4, 2023 5:49 PM > > > > Legacy can utilize the 1.x hw plumbing without building new hypothetical PF > > hardware. > > > > Maybe. > > Whether 1.x BAR can be reused for legacy would depend on a bunch of factors. > > E.g. with 1.x using VIRTIO_F_NOTIF_CONFIG_DATA - probably not. > > > Not really because legacy doesn't have that feature. > Legacy notifications are subset of 1.x feature. > This was also discussed. So for legacy such hardware will likely not want to use the same BAR. > > Let's just say, we are not in the position where we dictate these things to OS > > vendors yet. One of motivations of the spec is making writing drivers easier so > > let's add an option for that pls. > > > There is no need to add multiple options at this point when the hw vendors are not going to implement. > When we find another vendor to implement, we can always add the new method. > Marvell and Nvidia both are forwarding with AQ at present proposal. > > > > VF has BAR for driver notifications. This BAR is used for 1.x and legacy. > > > > But it's the same piece of silicon - be it in PF or in VF. > > I really don't see why it matters. > > > In same piece of silicon one needs to open yet another PCI steering entry to tell that treat this for VF. > This double size programming is useless. > > Yet again we are discussing same point as before. > > > > There is no need to ask vendors to build new HW to put driver notifications > > on the PF BAR for VFs, when it already exists on the VF. > > I'm talking about giving vendors an option not asking them. > > > Ok. Understood. > When a vendor prefers to implement such cross hw forwarding it can be done. > There isn't a desire to burn and program extra hw for functionality that already exists on the VF. > Hence, VF's doorbell on PF can be parked for the future option when one actually wants to implement it. I reached out to windows team to know how big a problem this is. Let's see. I have another idea meanwhile: VF already has notification capability. The only issue is offset has to be queried through modern BAR. How about we agree that for legacy, we just agree that offset 0 is used? Does not sound like a big sacrifice of memory to me, and we completely avoid the new command and the need to tie PF and VF. -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org