Oldest supported Xen version in upstream QEMU (Was: Re: [Minios-devel] [PATCH v2 0/15+5+5] Begin to disentangle libxenctrl and provide some stable libraries)

[Ian Campbell <ian.campbell@citrix.com>]

(dropping minios-devel)

Stefano,

On Wed, 2015-07-15 at 16:46 +0100, Ian Campbell wrote:
> 
> There are 3 series, against xen.git (15 patches), mini-os.git (5
> patches) and qemu-xen-trad.git (5 patches). The patches against xen.git
> point to the patches in the other two trees via instructions to update
> the relevant Config.mk field. The perils of changing unstable
> interfaces!

I started looking into making the appropriate changes to QEMU upstream to
use the new libraries directly.

QEMU (in include/hw/xen/xen_common.h) includes compat shims for libxenctrl
versions back as far as 3.3.0.

The main distinction is between pre-4.1.0 and 4.1.0 and later, since
various handles switching from int's to opaque pointers at that point,
meaning there are some typedefs and wrappers for things.

My plan was to rework the QEMU code to use only the new library function
names for everything such that this becomes the default case (which makes
sense given these libraries are intended to be long term stable) and to
update the code in xen_common.h to bridge the gap to 4.6 and earlier.

But I'm having to jump through some hoops in order to support the pre-4.1.0
version of things. It's not impossible to support it, I'm sure, but things
would be a lot easier if we could just drop that support code.

Can we consider dropping support for Xen 4.0 and earlier from upstream QEMU
at this point?

Some data: Xen 4.0.0 was released in April 2010, the last point release was
4.0.4 in August 2012 and we no longer do security support for it (for a
year or two now, I think).

Thanks,
Ian.