From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-7551-cohuck=redhat.com@lists.oasis-open.org Sender: 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 5572F985E55 for ; Wed, 15 Jul 2020 13:29:08 +0000 (UTC) References: <87r1tdydpz.fsf@linaro.org> <20200715114855.GF18817@stefanha-x1.localdomain> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20200715114855.GF18817@stefanha-x1.localdomain> Date: Wed, 15 Jul 2020 14:29:04 +0100 Message-ID: <877dv4ykin.fsf@linaro.org> MIME-Version: 1.0 Subject: Re: [virtio-dev] On doorbells (queue notifications) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable To: Stefan Hajnoczi Cc: virtio-dev@lists.oasis-open.org, Zha Bin , Jing Liu , Chao Peng List-ID: Stefan Hajnoczi writes: > On Tue, Jul 14, 2020 at 10:43:36PM +0100, Alex Benn=C3=A9e wrote: >> I'm slightly confused by the MSI terminology because this only seems to >> be relevant for the PCI legacy interface and AFAICT only touch the >> outgoing path in setup and del_vq. Do incoming MSI interrupts just get >> mapped directly to the appropriate handler function to process the >> queues or the config? > > When MSI is used the VIRTIO ISR register does not need to be read by the > guest interrupt handler. > >> Finally I'm curious if this is just a problem avoided by the s390 >> channel approach? Does the use of messages over a channel just avoid the >> sort of bouncing back and forth that other hypervisors have to do when >> emulating a device? > > What does "bouncing back and forth" mean exactly? Context switching between guest and hypervisor. > > Stefan --=20 Alex Benn=C3=A9e --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org