From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1531-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 BA5ED98619A for ; Fri, 20 Nov 2020 15:13:44 +0000 (UTC) Date: Fri, 20 Nov 2020 16:13:30 +0100 From: Cornelia Huck Message-ID: <20201120161330.740d694e.cohuck@redhat.com> In-Reply-To: <20201116191629.47661-1-david@redhat.com> References: <20201116191629.47661-1-david@redhat.com> MIME-Version: 1.0 Subject: [virtio-comment] Re: [PATCH v1] virtio-mem: minor clarification regarding read-access to unplugged blocks Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: David Hildenbrand Cc: virtio-comment@lists.oasis-open.org, teawater , Marek Kedzierski , "Michael S . Tsirkin" List-ID: On Mon, 16 Nov 2020 20:16:29 +0100 David Hildenbrand wrote: > Let's clarify that we don't expect all DMA to work with unplugged blocks. > We really only give guarantees when reading from unplugged memory blocks > via the CPU, e.g., as done by Linux when creating a system dump via > kdump: the new kernel will copy the content of the old (crashed) kernel > via the CPU to user space, from where it will find its final destination > inside the dump file. Note that dumping via makedumpfile under Linux will > avoid reading unplugged blocks completely. > > This is a preparation for device passthrough to VMs, whereby such > dedicated devices might not be able to read from unplugged memory blocks. > > Let's document that this scenario is possible, and why this handling is > in place at all. > > Cc: teawater > Cc: Marek Kedzierski > Cc: Michael S. Tsirkin > Cc: Cornelia Huck > Signed-off-by: David Hildenbrand > --- > virtio-mem.tex | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) Looks reasonable to me. Acked-by: Cornelia Huck 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/