Re: preparations for 4.15.1 and 4.13.4

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.07.2021 19:16, Andrew Cooper wrote:
> On 15/07/2021 08:58, Jan Beulich wrote:
>> Beyond this I'd like the following to be considered:
>>
>> 6409210a5f51 libxencall: osdep_hypercall() should return long
>> bef64f2c0019 libxencall: introduce variant of xencall2() returning long
>> 01a2d001dea2 libxencall: Bump SONAME following new functionality
>> 6f02d1ea4a10 libxc: use multicall for memory-op on Linux (and Solaris)
>>
>> If those are to be taken (which means in particular if the question of
>> the .so versioning can be properly sorted),
>>
>> 198a2bc6f149 x86/HVM: wire up multicalls
> 
> We can backport changes in SONAME safely so long as:
> 
> 1) We declare VERS_1.2 to be fixed and released.  This means that we
> bump to 1.3 for the next change, even if it is ahead of Xen 4.16 being
> release, and

Right. A matter of remembering at the right point (if need be). That's
where I think the risk is. (And of course I understand you meaning
VERS_1.3 and VERS_1.4 respectively for "fixed and released" and "bump
to".)

If we did so, what I can't tell offhand is whether any ABI-checker
data would need updating then.

> 2) *All* ABI changes up to VERS_1.2 are backported.
> 
> 
> The ABI called VERS_1.2 must be identical on all older branches to avoid
> binary problems when rebuilding a package against old-xen+updates, and
> then updating to a newer Xen.

I'm afraid I'm less clear about this part: There shouldn't be any ABI
differences in VERS_1.2 in the first place, should there? Or, if the
number is again off by one, the sole new function would be identical
(ABI-wise) everywhere.

Jan