Re: [PATCH V5 04/22] xen/ioreq: Make x86's IOREQ feature common

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 27 Jan 2021, Oleksandr wrote:
> > > > On Mon, 25 Jan 2021 at 19:09, Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>
> > > > wrote:
> > > > > ***
> > > > > Please note, this patch depends on the following which is
> > > > > on review:
> > > > > https://patchwork.kernel.org/patch/11816689/
> > > > > The effort (to get it upstreamed) was paused because of
> > > > > the security issue around that code (XSA-348).
> > > > > ***
> > > > I read this comment as "This series should be applied on top the patch
> > > > X". However, looking at your branch, I can't see the patch. What did I
> > > > miss?
> > > You didn't miss anything. Patch series doesn't contain it. I mentioned
> > > about this patch in order not to forget about it
> > > and draw reviewer's attention. Looks like, the activity (to get it
> > > upstreamed) hasn't been resumed yet and I don't know what we should do
> > > with that dependency
> > > in the context of this series...
> > 
> > I will reply what I wrote on IRC privately :). I think this fine to defer it
> > to after Xen 4.15 because IOREQ will be in tech preview.
> 
> Thank you. I got a request to make a possibility for user to select IOREQ via
> the menuconfig on Arm. Saying tech preview do you mean that I also need to put
> it under CONFIG_EXPERT on Arm?

Normally I would say that unless it actually takes an expert to enable
the feature, it is better to make it depend on CONFIG_UNSUPPORTED [1].

However, in this case, it might actually take an expert :-)
Additional patches are still required to enable the feature at the
toolstack level, and also the user needs to build a userspace ioreq
server. So in this case I am fine either way. I'll leave it up to you
and Julien to pick the best one.

Either way, please add "(EXPERT)" or "(UNSUPPORTED)" in the one-line
kconfig description for ARM if possible.


[1] https://marc.info/?l=xen-devel&m=161168780401884