On Thu, May 11, 2023 at 2:47 PM Conor Dooley <conor@xxxxxxxxxx> wrote: > > On Thu, May 11, 2023 at 02:27:44PM -0700, Atish Patra wrote: > > > > The other thought I had was that perhaps some software may choose not to > > > implement version x.y.0 of an extension and only support x.z.0, z > y > > > for some reason. We'd want to refuse that extension if the extension is > > > found, but the version is not listed as being something compatible with > > > x.z.0, and while the ISA spec does say that the default assumption is > > > 2p0 for unversioned extensions in its current form, I struggle to > > > extrapolate that to extensions not currently part of the unpriv spec, > > > but rather defined on their own. > > > > > > > That's a fair point. However, any new RVI ISA extension will only have v1.0 > > as per my knowledge. Any new feature will have to be part of a > > different extension. > > At least that was the plan discussed last year. > > That's more than last year at this point, and nothing has changed in the > documentation! Talk's cheap, ehh? > Yup. I will poke RVI folks to check if it still is the plan or changed !! > > https://github.com/riscv/riscv-isa-manual/issues/781#issuecomment-983222655 > > > > Are you aware of any discussion that changes this ? > > It's called "trust issues". I am far less worried about the addition of > new features though than the removal of existing ones. > Part of me fears for fence.i-less systems for example, but there would > be other ways to bodge around the mess if it comes to pass. > If we are *sure* that no extensions will modify features additively or > subtractively, then this may not be needed at all & I can avoid having > to bend dt-validate to my will. Fair enough. Let's get some clarification first from RVI. It must be documented in unpriv spec. Otherwise, there is no point of promise :) > We have no guarantees for vendor extensions on that front either, > they're free to do what they like w.r.t. versioning, no? Vendor extensions are wild west. Who knows what scheme they will use. We will likely have a vendor specific string parsing logic. They can do whatever in that to figure out the version if they require it. -- Regards, Atish
