[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: Re: [PATCH v3 1/2] virtio-net: Describe dev cfg fields read only
On Wed, Feb 22 2023, "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Wed, Feb 22, 2023 at 01:07:07PM +0100, Cornelia Huck wrote: >> On Wed, Feb 22 2023, "Michael S. Tsirkin" <mst@redhat.com> wrote: >> >> > On Wed, Feb 22, 2023 at 10:01:24AM +0100, Cornelia Huck wrote: >> >> On Tue, Feb 21 2023, "Michael S. Tsirkin" <mst@redhat.com> wrote: >> >> >> >> > On Tue, Feb 21, 2023 at 05:59:52PM +0000, Parav Pandit wrote: >> >> >> >> >> >> > From: Michael S. Tsirkin <mst@redhat.com> >> >> >> > Sent: Tuesday, February 21, 2023 12:52 PM >> >> >> > >> >> >> > On Tue, Feb 21, 2023 at 05:50:09PM +0000, Parav Pandit wrote: >> >> >> > > Hence, it should be mentioned as read-only fields, so when the driver writes >> >> >> > something to read-only fields, it can be considered as undefined behavior on >> >> >> > such fields. >> >> >> > > >> >> >> > >> >> >> > In the description not in the normative statements. normative sections just tell >> >> >> > driver what it must and must not do, in the standard RFC terms. >> >> >> > >> >> >> Got it. >> >> >> I will shift them as read-only in the description section. >> >> >> And normative in the device and driver section. >> >> >> Device section: >> >> >> Any writes to config space fields is ignored by the device, because these are read-only fields for the driver. >> >> > >> >> > writes is plural so "are ignored" >> >> > >> >> > but more importantly use rfc terms in normative sections. >> >> >> >> I don't think you need to talk about "read-only" in the normative >> >> sections (that belongs to the descriptive sections.) I'd use >> >> >> >> "The device MUST ignore any writes to config space fields by the >> >> driver." >> > >> > Hmm. Is this something we previously required for read only fields? >> >> So, better make it SHOULD? >> >> (The only alternative to ignoring I see is breaking the device, and I >> think ignoring is preferable.) > > We can just skip adding a new requirement completely - we'll never get > there with a compliant driver. This is what we do e.g. for MMIO. > Why not? That would be fine with me as well. > This has an advantage as this allows backing config with regular RAM. > Also I feel that since it always said "read only for driver" then > this implies a restriction on driver not the device. Indeed. The normative statement below should be enough to make that "read-only for the driver" thing obvious. > >> > >> > >> >> > >> >> >> >> >> >> Driver section: >> >> >> Driver must not write to read-only fields. >> >> >> >> "The driver MUST NOT write to any config space field."
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]