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 6BFDDC4167B for ; Wed, 6 Dec 2023 10:17:38 +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 8E1EF2AC62 for ; Wed, 6 Dec 2023 10:17:37 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 70E5C9868F3 for ; Wed, 6 Dec 2023 10:17:37 +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 56F129866C1; Wed, 6 Dec 2023 10:17:37 +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 481659867BC for ; Wed, 6 Dec 2023 10:17:37 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: spDXhwb5ObuOZZss4mUHXg-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701857851; x=1702462651; h=in-reply-to:content-transfer-encoding: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=ZthwVw7KjsI8I+9PlqnZOgHm5xy7kHr5KidQMVYQcGE=; b=intVcqXmILD6ifRyGzsefxo8KsiXknHcLerpC02sUWVSIQSIiqoVXcUVGW85agfDiL YFFoh02j46JUqibBGSY+3x1vMwf++U/vbL/XO7bwdoIkX5zbuOFzKtkifLqjUCDJijSw /5KRTPuXACjWKNM1EmN9pOLTaOCFgqfpUh623DUxovZti4detADdUyh7tqGs8Bw5iy58 Kh5yNpUA40t1r+lfVKlZRG+qUZN2kLKmIAQOMQl17Xa2xsGK6ICHHoG4FgM9Wdf9oj+S nZYQ8AGNq2yCFv2RgivETM0HRUef2kCVppiQ+Ri2U1y7dHkVg5TcJpiFR5DsAkAG86e8 aWNA== X-Gm-Message-State: AOJu0YyAetnVzjSYw9ytWfOMV7iLXcfKbC2u6F5oTnEiinbHcvO1iUNH QPI3R4CVwZXMwp40B0dqI1BotK7lN8N874tLfRMw4YKnS+AKjIkuWPg81OoWdt6C+oL0q7OXzif BZx/0mKKN+jI140C3AzAjEO1soJCY X-Received: by 2002:a2e:86da:0:b0:2c9:f37a:c018 with SMTP id n26-20020a2e86da000000b002c9f37ac018mr347174ljj.25.1701857851053; Wed, 06 Dec 2023 02:17:31 -0800 (PST) X-Google-Smtp-Source: AGHT+IGPl8+fLS9RfwmDYMetZQ9bkpoS0MlfW2jFfAgydrG6qT7Zx2NnrC+7cBxEh2HmfXbGBidJAg== X-Received: by 2002:a2e:86da:0:b0:2c9:f37a:c018 with SMTP id n26-20020a2e86da000000b002c9f37ac018mr347167ljj.25.1701857850675; Wed, 06 Dec 2023 02:17:30 -0800 (PST) Date: Wed, 6 Dec 2023 05:17:27 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: David Stevens , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org Message-ID: <20231206051652-mutt-send-email-mst@kernel.org> References: <20231204094123.856214-1-stevensd@chromium.org> <20231204094123.856214-2-stevensd@chromium.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [virtio-comment] [PATCH v3 1/1] Define a low power mode for devices On Wed, Dec 06, 2023 at 05:16:04PM +0800, Jason Wang wrote: > On Tue, Dec 5, 2023 at 6:58 PM David Stevens wrote: > > > > On Tue, Dec 5, 2023 at 1:18 PM Jason Wang wrote: > > > > > > On Mon, Dec 4, 2023 at 5:41 PM David Stevens wrote: > > > > > > > > Define a low power mode for virtio devices where the devices are > > > > expected to maintain their state. This gives drivers an option for power > > > > management besides simply resetting their device. In the virtualization > > > > use case, this allows the guest to be suspended even with stateful > > > > virtio devices like gpu and fs. > > > > > > > > Low power mode is primarily defined at the transport layer. The only > > > > part that depends on device-type specific details is whether a given > > > > virtqueue is device driven or driver driven. > > > > > > > > This change only defines the transport-specific implementation for > > > > Virtio over PCI. > > > > > > A dumb question, if this is only for PCI, can the device just > > > implement no_soft_reset via PMC? > > > > This is basically No_Soft_Reset, yes. If a change similar to [1] would > > be acceptable based only on the No_Soft_Reset bit even with no concept > > of power management in the virtio spec, then I personally don't have > > any problems with that. > > > > [1] https://lore.kernel.org/lkml/20231113055138.117392-1-stevensd@chromium.org/ > > So if I read the code correctly, the current Qemu advertises PM but > without no_soft_reset. > > So this patch seems to break e.g virtio-net and doesn't fix virtio-GPU. > > Thanks > > > > > -David > > what is the breakage exactly? Maybe we need a new feature bit? -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org