From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-668-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Date: Wed, 27 Feb 2019 14:56:52 +0100 From: Cornelia Huck Message-ID: <20190227145652.22286c72.cohuck@redhat.com> In-Reply-To: <20190225184506.GF2710@work-vm> References: <20190222115433.7160-1-dgilbert@redhat.com> <20190222115433.7160-4-dgilbert@redhat.com> <20190225165014.GE379@stefanha-x1.localdomain> <20190225184506.GF2710@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [virtio-comment] Re: [PATCH v2 3/3] shared memory: Define mmio registers To: "Dr. David Alan Gilbert" Cc: Stefan Hajnoczi , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org List-ID: On Mon, 25 Feb 2019 18:45:06 +0000 "Dr. David Alan Gilbert" wrote: > * Stefan Hajnoczi (stefanha@redhat.com) wrote: > > On Fri, Feb 22, 2019 at 11:54:33AM +0000, Dr. David Alan Gilbert (git) wrote: > > > + region, as defined by the device for the region selected by > > > + the \field{SHMId} register. Reading from a non-existent > > > + region (i.e. where the ID written to \field{SHMId} is unused) > > > + results in a length of -1. > > > > -1 is used to indicate the absence of a region, does 0 have a meaning? > > No, I'd be happy to switch; although this does lead to another question; > what happens on an older virtio-mmio implementation when a device > tries to read these registers to detect if the region exists? You probably mean that the driver is reading, right? Not sure if we ever specified what happens if a driver interacts with a register that was not specified when the device was written... maybe we need to bump the device version number? But that would break old drivers if they get a 3 but expected a 2. This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/