[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Stable library ABI compatibility checking

  • To: <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Thu, 11 Feb 2021 12:17:26 +0000
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=0yPHMVpqh8KgihOcoJHIkFlCwxhj0MXJpGUALjSmcm0=; b=FJPM4l2qcw4j7/WlPNrBzwsh6pkNzgigUALMoK3A6TNzHr9PTe99Mw1Wk31gybbmf2+ZbhlH5HdMou3oa2NTEG3CxCuQBY8wPozLGLAHqbFehDRnfO4AXg6QEuh8B6Xlr509kjKAnvVn8OoMZSrLzoyRCrZzGmScKwrRvvexDKbw1NpAQjRbICuyvBL3i86wZnWdg8i2DqGRS6M38uien539K7MngNPSGqh6b0MTJwd59K3wHSgV53uGPV3Q/cwrGBFj02fQaFqfv8FqjsgXoGdJB2pzyJOxddJvBKdLjJSbj5320SdAqyWloebxjYU2YulRs6Jo19qV4eDaOB+1MQ==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=OZQhSsRPphNHbgeN8R9T6bq2OORs14WLMtW5k1YpGfCHY6ow3TtvoTRYjys4GgJut43pr9QG8gZrF54tDWGm9FISrwRnjaWDzfnRiSH2e8CEBQd5S3afnV122LfFetXYBJc5GE5bfG8WcbCju85nUbRUWZNFkGKZ5eTsp5oLJFzGXXprwApFsQt/dodvZiWpE9OED3E04J/Yu+VdMYNCQL1upuRNdLCBhT/Z3RgQGPxfT8QxfCCkeBis24tug6gX2c5Xi2ajDEI6KXJfhVRV28G8WKOwIAMJstt2k93r6PB2SH0V51V6O4i1wM5mU1PZs7Sr6nH7UrBDSx5YIGvM3Q==
  • Authentication-results: esa6.hc3370-68.iphmx.com; dkim=pass (signature verified) header.i=@citrix.onmicrosoft.com
  • Delivery-date: Thu, 11 Feb 2021 12:17:45 +0000
  • Ironport-sdr: DCrIMEkgX54EbOCwOsgaZOMjc1upsJou9A9Ae6RfKejq1IpeeIYwUd2XZ3DQREBFIxiekZbY+u XTJ+G1mNepDYyWWjikctD5dXPI6caHj1XB674+o78ie80YRIGgNU5Q1ei8DyTqTP3fghtJ6B/Q YIDGZmdweXuHEninK+UKtT9V/oJAV+vu8kg81AtRlYhn9vYhtNkFyMxY1UN48ZBLcw5k1fZ5er EJ0HuscmauGUiqJ65b/Pqwy57gNrZuwfAC9UPBLiESEHh0Gs+EEH5Zu+qYsm0CY2IdXo3Yxysq XG0=
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 11/02/2021 11:53, Jan Beulich wrote:
> On 11.02.2021 12:30, Andrew Cooper wrote:
>> On 11/02/2021 11:05, Jan Beulich wrote:
>>> On 11.02.2021 02:08, Andrew Cooper wrote:
>>>> Hello,
>>>> Last things first, some examples:
>>>> http://xenbits.xen.org/people/andrewcoop/abi/libxenevtchn-1.1_to_1.2.html
>>>> http://xenbits.xen.org/people/andrewcoop/abi/libxenforeignmemory-1.3_to_1.4.html
>>>> These are an ABI compatibility report between RELEASE-4.14.0 and staging.
>>>> They're performed with abi-dumper (takes a shared object and header
>>>> file(s) and write out a text "dump" file which happens to be a perl
>>>> hash) and abi-compliance-checker checker, which takes two dumps and
>>>> produces the HTML reports linked above.  They're both debian tools
>>>> originally, but have found their way across the ecosystem.  They have no
>>>> impact on build time (when invoked correctly).
>>>> I'm encouraged to see that the foreignmem analysis has even spotted that
>>>> we deliberately renamed one parameter to clarify its purpose.
>>>> For the stable libraries, the RELEASE-$X.$Y.0 tag is the formal point
>>>> when accumulated changes in staging become fixed.  What we ought to be
>>>> doing is taking a "dump" of libraries at this point, and publishing
>>>> them, probably on xenbits.
>>>> Subsequent builds on all the staging branches should be performing an
>>>> ABI check against the appropriate lib version.  This will let us catch
>>>> breakages in staging (c/s e8af54084586f4) as well as breakages if we
>>>> ever need to backport changes to the libs.
>>>> For libraries wrapped by Juergen's tools/libs/ common-makefile changes,
>>>> adding ABI dumping is easy.  The only complicating is needing to build
>>>> everything with "-Og -g", but this is easy to arrange, and frankly ought
>>>> to be the default for debug builds anyway (the current use of -O0 is
>>>> silly and interferes with common distro hardening settings).
>>>> What I propose is tweaking the library build to write out
>>>> lib$FOO.so.$X.$Y-$(ARCH).abi.dump files.  A pristine set of these should
>>>> be put somewhere on xenbits, and a task put on the release technicians
>>>> checklist for future releases.
>>>> That way, subsequent builds which have these tools available can include
>>>> a call to abi-compliance-checker between the authoritative copy and the
>>>> one from the local build, which will make the report available, and exit
>>>> nonzero on breaking problems.
>>>> To make the pristine set, I need to retrofit the tooling to 4.14 and
>>>> ideally 4.13.  This is in contravention to our normal policy of not
>>>> backporting features, but I think, being optional build-time-only
>>>> tooling, it is worthy of an exception considering the gains we get
>>>> (specifically - to be able to check for ABI breakages on these branches
>>>> in OSSTest).  Backporting to 4.12 and older is far more invasive, due to
>>>> it being before the library build systems were common'd.
>>>> Anyway, thoughts?
>>> +1
>>> Not sure about the backporting effects - tools/libs/ had quite a bit
>>> less content in 4.14 and older, so the coverage would be smaller.
>> tools/libs/ has been the stable libraries, since IanC split them years
>> ago.  The only odd-one-out is libxenstored IIRC, which moved during the
>> 4.15 window.
> As well as ctrl/, guest/, light/, stat/, util/, and vchan/.

Right, but 5 of those don't have stable ABIs.




Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.