Re: Support of old Xen versions in the Linux kernel

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 13 Apr 2021, Boris Ostrovsky wrote:
> On 4/13/21 2:14 AM, Juergen Gross wrote:
> > In x86 kernel development the question came up whether we need to
> > support XENFEAT_gnttab_map_avail_bits not being set when running as a PV
> > guest.
> >
> > This feature is active for PV guests since Xen 3.4.
> >
> > So the basic question is: which is the oldest version of Xen we want to
> > support in the Linux kernel? As far as I know there is no Xen based
> > product in productive use with Xen older than 4.2.
> >
> > Would we be fine to drop support for older versions (feel free to
> > suggest other versions than 4.2 as the first to be supported Xen
> > version)?
> >
> > In case the answer is yes, I'd post some patches to clean up the kernel,
> > including a safety net to bail out in case a feature needed isn't
> > available.
> 
> Sounds good to me.

For ARM, the Xen ABI became stable only with Xen 4.4.