[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: Re: [virtio-dev] [PATCH] split-ring: Demand that a device must not change descriptor entries
On Mon, Nov 11, 2019 at 06:26:58PM +0100, Jan Kiszka wrote: > On 11.11.19 18:17, Rob Miller wrote: > > what is trying to be solved here? There is a reason why this is allowed > > as some vendors update the table when using RX_MERABLE_BUFFERs & > > F_IN_ORDER features > > OK, good to know. Which fields are updated then? Under which conditions (ie. > in which states of the device)? > > The background is in the link below. My goal was to find a simple way > declaring all fields read-only for the device to avoid problems with new > implementations. But it looks like it's more complicated... > > Jan No answer yet. Rob I see the following options: - proceed with the ballot as is ignoring your comment. Maybe it's all a misunderstanding? It could be the comment was referring to the packed ring, where this patch refers to the split ring. - make it weaker: MUST if PLATFORM_ACCESS is negotiated, and SHOULD if it isn't. > > > > Rob Miller > > rob.miller@broadcom.com <mailto:rob.miller@broadcom.com> > > (919)721-3339 > > > > > > On Mon, Nov 11, 2019 at 12:13 PM Jan Kiszka <jan.kiszka@siemens.com > > <mailto:jan.kiszka@siemens.com>> wrote: > > > > From: Jan Kiszka <jan.kiszka@siemens.com > > <mailto:jan.kiszka@siemens.com>> > > > > So far the spec only indirectly says that a descriptor table entry is > > not modified by a device when processing it. Make this explicit by > > adding it as normative requirement. Existing drivers already depend on > > this. > > > > See also > > https://lists.oasis-open.org/archives/virtio-dev/201910/msg00057.html. > > > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com > > <mailto:jan.kiszka@siemens.com>> > > --- > > split-ring.tex | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/split-ring.tex b/split-ring.tex > > index 123ac9f..bfef62d 100644 > > --- a/split-ring.tex > > +++ b/split-ring.tex > > @@ -217,7 +217,7 @@ \subsection{The Virtqueue Descriptor > > Table}\label{sec:Basic Facilities of a Virt > > \devicenormative{\subsubsection}{The Virtqueue Descriptor > > Table}{Basic Facilities of a Virtio Device / Virtqueues / The > > Virtqueue Descriptor Table} > > A device MUST NOT write to a device-readable buffer, and a device > > SHOULD NOT > > read a device-writable buffer (it MAY do so for debugging or > > diagnostic > > -purposes). > > +purposes). A device MUST NOT write to any descriptor table entry. > > > > \drivernormative{\subsubsection}{The Virtqueue Descriptor > > Table}{Basic Facilities of a Virtio Device / Virtqueues / The > > Virtqueue Descriptor Table} > > Drivers MUST NOT add a descriptor chain longer than $2^{32}$ bytes > > in total; > > -- 2.16.4 > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > > <mailto:virtio-dev-unsubscribe@lists.oasis-open.org> > > For additional commands, e-mail: > > virtio-dev-help@lists.oasis-open.org > > <mailto:virtio-dev-help@lists.oasis-open.org> > > > > -- > Siemens AG, Corporate Technology, CT RDA IOT SES-DE > Corporate Competence Center Embedded Linux > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]