llvm dev - Sep 2016 - [cfe-dev] Revisiting our informal policy to support two versions of MSVC

Hi,

As I understand it the specific issue we're seeing is related to what
Martin described. But due to numerous bugs found when mixing objects
compiled with different versions of MSVC in the past, we now are shy of
doing it even if it seems to work superficially - that's no guarantee bugs
won't be found down the line. We'd much prefer to stay within the realms
of
what Microsoft support.

Cheers,

James
On Wed, 7 Sep 2016 at 20:53, Craig, Ben via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Note that this is intentional from the MSVC C++ library implementation
> side of things.  For major versions, no attempt is made to preserve library
> ABI compatibility.
> I am aware of a language ABI break in VC++ 2013.
>
https://randomascii.wordpress.com/2013/12/01/vc-2013-class-layout-change-and-wasted-space/
>
> I'm not currently aware of any on the VC++ 2015 side of things, but
that
> doesn't mean much.
>
>
> On 9/7/2016 2:34 PM, Martin O'Riordan via llvm-dev wrote:
>
> Apart from the obvious licencing issues, each time I have moved from one
> version of VC++ to another, the big problem I have had is not specifically
> the ABI at the register passing, stack organisation level, but rather the
> implementation details of the Standard C++ libraries, and in particular the
> STL containers.
>
> While the compiler team puts considerable effort into maintaining the ABI,
> the C++ library implementation usually changes a lot.
>
> Since this is largely in the form of very complex headers defining
> templates which in turn cause other helper templates to be used, it is here
> that I find things go awry.
>
> So for C++, a function like:
>
> std::list<int> foo();
>
> seems simple enough, but if the caller and the callee are compiled with
> different versions, it usually won't work because of some artefact of
the
> STL implementation tuning that occurs between versions.  In particular,
> this impacts things like using C++ interfaces across DLLs and in
> pre-compiled libraries.
>
> I think that the ABI maintenance in this case tends to be for C and POD
> compatability, but not for the higher level C++ compatability which is
> unfortunate and restricts how we can use C++.
>
> Is it possible that it is this aspect of the version change that is
> causing your ABI difficulties?
>
> MartinO
>
>
> On 7 September 2016 at 20:18, Zachary Turner via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Can you elaborate on the abi incompatibility? I thought there were no
>> breaks
>> On Wed, Sep 7, 2016 at 7:59 AM James Molloy via cfe-dev <
>> cfe-dev at lists.llvm.org> wrote:
>>
>>> Hi all,
>>>
>>> Firstly sorry I'm a bit late responding on this one. Internally
to ARM
>>> we build LLVM for Windows. Our current build cluster has only
VS2013
>>> installed and as a result of this thread we've been working on
getting
>>> VS2015 installed. This involves a certain amount of IT-wrangling as
the
>>> cluster we use is company-wide. There have been some hiccups
regarding
>>> licensing of MSVC professional (we can't use the community
edition for the
>>> same reasons mentioned by Paul previously) but we hoped to be ready
in time
>>> for the 15th September switchover date.
>>>
>>> It's recently been realised that VS2013 and VS2015 are not ABI
>>> compatible (something that really surprised me), and this means we
have to
>>> synchronize moving LLVM's build to VS2015 as well as upgrading
a third
>>> party library that we receive from the vendor in compiled library
form.
>>> This is not something we're capable of doing by September 15th.
>>>
>>> We try really hard at ARM to hide our internal processes because we
>>> believe that they're on the whole irrelevant to the community,
however in
>>> this case we'd be really stuck, unable to get production
builds.
>>>
>>> As this is an ABI-incompatible upgrade, and it's changing the
informal
>>> policy on upgrades, could we please have some more grace time?
Ideally
>>> another month, so the 15th October. If we haven't sorted it by
then, it's
>>> our problem.
>>>
>>> Cheers,
>>>
>>> James
>>>
>>> On Thu, 1 Sep 2016 at 21:06 Mehdi Amini via cfe-dev <
>>> cfe-dev at lists.llvm.org> wrote:
>>>
>>>> On Sep 1, 2016, at 1:05 PM, Reid Kleckner <rnk at
google.com> wrote:
>>>>
>>>> On Thu, Sep 1, 2016 at 12:53 PM, Mehdi Amini via cfe-dev <
>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>
>>>>> Isn’t a big (the most) reason for supporting “old”
toolchains to allow
>>>>> downstream users to upgrade with some flexibility?
>>>>> If I have a large codebase that is using LLVM (let say a
few custom
>>>>> backends), and is validated with “MSVC 2013”, I can upgrade
to “2015” but I
>>>>> will need some qualification/validation: this is not free
and take some
>>>>> time. If you drop aggressively supports for “old” toolchain
it means that
>>>>> I’m either stuck with an “old” LLVM or that I have to
update earlier than
>>>>> expected.
>>>>>
>>>>> Isn’t this usually balanced in upstream LLVM to upgrade
when there is
>>>>> a real *benefit* to it?
>>>>> I’m mentioning it because it seems to conflict with the
"always
>>>>> upgrade to the newest one unless there are serious issues
with it” you
>>>>> mentioned above.
>>>>>
>>>>
>>>> I agree, we should raise the minimum VS version requirement
when the
>>>> benefits to the LLVM community outweigh the costs of switching
for major
>>>> LLVM contributors and users. I think we'll always make that
decision in the
>>>> same way: by raising it on the mailing lists and discussing the
pros and
>>>> cons. That's basically what David said when he kicked this
whole discussion
>>>> off, anyway:
>>>>
>>>> """But if we find ourselves in a situation where
asking folks to
>>>> upgrade to a compiler which has been widely deployed soothes
development
>>>> for the greater LLVM community, we should consider dropping
support for the
>>>> older versions of that compiler."""
>>>>
>>>> I think everything is working as intended here.
>>>>
>>>>
>>>> Right, to be clear there is no misunderstanding: I was
absolutely not
>>>> suggesting the opposite when answering Zach..
>>>>
>>>> —
>>>> Mehdi
>>>>
>>>>
>>>> We raised the VS 2013 upgrade issue, discussed it, determined
that it
>>>> was holding us back, and now we're doing the upgrade. If VS
"15" brings
>>>> major language compatibility improvements, I imagine we'll
be having this
>>>> same discussion again next year. If it doesn't, and
supporting 2015 and
>>>> "15" at the same time has the same cost, then we
won't bother raising the
>>>> floor for a while.
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-dev mailing list
>>>> cfe-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>
>
> _______________________________________________
> LLVM Developers mailing listllvm-dev at
lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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It's worth pointing out that from 2015 and on, they claim to support full
forwards compatibility of the standard libraries, so this should (in
theory) never be an issue again.

On Wed, Sep 7, 2016 at 1:12 PM James Molloy via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi,
>
> As I understand it the specific issue we're seeing is related to what
> Martin described. But due to numerous bugs found when mixing objects
> compiled with different versions of MSVC in the past, we now are shy of
> doing it even if it seems to work superficially - that's no guarantee
bugs
> won't be found down the line. We'd much prefer to stay within the
realms of
> what Microsoft support.
>
> Cheers,
>
> James
> On Wed, 7 Sep 2016 at 20:53, Craig, Ben via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Note that this is intentional from the MSVC C++ library implementation
> side of things.  For major versions, no attempt is made to preserve library
> ABI compatibility.
> I am aware of a language ABI break in VC++ 2013.
>
https://randomascii.wordpress.com/2013/12/01/vc-2013-class-layout-change-and-wasted-space/
>
> I'm not currently aware of any on the VC++ 2015 side of things, but
that
> doesn't mean much.
>
>
> On 9/7/2016 2:34 PM, Martin O'Riordan via llvm-dev wrote:
>
> Apart from the obvious licencing issues, each time I have moved from one
> version of VC++ to another, the big problem I have had is not specifically
> the ABI at the register passing, stack organisation level, but rather the
> implementation details of the Standard C++ libraries, and in particular the
> STL containers.
>
> While the compiler team puts considerable effort into maintaining the ABI,
> the C++ library implementation usually changes a lot.
>
> Since this is largely in the form of very complex headers defining
> templates which in turn cause other helper templates to be used, it is here
> that I find things go awry.
>
> So for C++, a function like:
>
> std::list<int> foo();
>
> seems simple enough, but if the caller and the callee are compiled with
> different versions, it usually won't work because of some artefact of
the
> STL implementation tuning that occurs between versions.  In particular,
> this impacts things like using C++ interfaces across DLLs and in
> pre-compiled libraries.
>
> I think that the ABI maintenance in this case tends to be for C and POD
> compatability, but not for the higher level C++ compatability which is
> unfortunate and restricts how we can use C++.
>
> Is it possible that it is this aspect of the version change that is
> causing your ABI difficulties?
>
> MartinO
>
>
> On 7 September 2016 at 20:18, Zachary Turner via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Can you elaborate on the abi incompatibility? I thought there were no
> breaks
> On Wed, Sep 7, 2016 at 7:59 AM James Molloy via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Hi all,
>
> Firstly sorry I'm a bit late responding on this one. Internally to ARM
we
> build LLVM for Windows. Our current build cluster has only VS2013 installed
> and as a result of this thread we've been working on getting VS2015
> installed. This involves a certain amount of IT-wrangling as the cluster we
> use is company-wide. There have been some hiccups regarding licensing of
> MSVC professional (we can't use the community edition for the same
reasons
> mentioned by Paul previously) but we hoped to be ready in time for the 15th
> September switchover date.
>
> It's recently been realised that VS2013 and VS2015 are not ABI
compatible
> (something that really surprised me), and this means we have to synchronize
> moving LLVM's build to VS2015 as well as upgrading a third party
library
> that we receive from the vendor in compiled library form. This is not
> something we're capable of doing by September 15th.
>
> We try really hard at ARM to hide our internal processes because we
> believe that they're on the whole irrelevant to the community, however
in
> this case we'd be really stuck, unable to get production builds.
>
> As this is an ABI-incompatible upgrade, and it's changing the informal
> policy on upgrades, could we please have some more grace time? Ideally
> another month, so the 15th October. If we haven't sorted it by then,
it's
> our problem.
>
> Cheers,
>
> James
>
> On Thu, 1 Sep 2016 at 21:06 Mehdi Amini via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> On Sep 1, 2016, at 1:05 PM, Reid Kleckner <rnk at google.com> wrote:
>
> On Thu, Sep 1, 2016 at 12:53 PM, Mehdi Amini via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Isn’t a big (the most) reason for supporting “old” toolchains to allow
> downstream users to upgrade with some flexibility?
> If I have a large codebase that is using LLVM (let say a few custom
> backends), and is validated with “MSVC 2013”, I can upgrade to “2015” but I
> will need some qualification/validation: this is not free and take some
> time. If you drop aggressively supports for “old” toolchain it means that
> I’m either stuck with an “old” LLVM or that I have to update earlier than
> expected.
>
> Isn’t this usually balanced in upstream LLVM to upgrade when there is a
> real *benefit* to it?
> I’m mentioning it because it seems to conflict with the "always
upgrade to
> the newest one unless there are serious issues with it” you mentioned
above.
>
>
> I agree, we should raise the minimum VS version requirement when the
> benefits to the LLVM community outweigh the costs of switching for major
> LLVM contributors and users. I think we'll always make that decision in
the
> same way: by raising it on the mailing lists and discussing the pros and
> cons. That's basically what David said when he kicked this whole
discussion
> off, anyway:
>
> """But if we find ourselves in a situation where asking
folks to upgrade
> to a compiler which has been widely deployed soothes development for the
> greater LLVM community, we should consider dropping support for the older
> versions of that compiler."""
>
> I think everything is working as intended here.
>
>
> Right, to be clear there is no misunderstanding: I was absolutely not
> suggesting the opposite when answering Zach..
>
> —
> Mehdi
>
>
> We raised the VS 2013 upgrade issue, discussed it, determined that it was
> holding us back, and now we're doing the upgrade. If VS "15"
brings major
> language compatibility improvements, I imagine we'll be having this
same
> discussion again next year. If it doesn't, and supporting 2015 and
"15" at
> the same time has the same cost, then we won't bother raising the floor
for
> a while.
>
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
>
>
> _______________________________________________
> LLVM Developers mailing listllvm-dev at
lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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I'll need to dig up the references for that... but I'm pretty sure the 
universal CRT that debuted in MSVC 2015 only covers the C parts, and not 
the C++ parts.


On 9/7/2016 4:28 PM, Zachary Turner wrote:
> It's worth pointing out that from 2015 and on, they claim to support 
> full forwards compatibility of the standard libraries, so this should 
> (in theory) never be an issue again.
>
> On Wed, Sep 7, 2016 at 1:12 PM James Molloy via llvm-dev 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>
>     Hi,
>
>     As I understand it the specific issue we're seeing is related to
>     what Martin described. But due to numerous bugs found when mixing
>     objects compiled with different versions of MSVC in the past, we
>     now are shy of doing it even if it seems to work superficially -
>     that's no guarantee bugs won't be found down the line. We'd
much
>     prefer to stay within the realms of what Microsoft support.
>
>     Cheers,
>
>     James
>     On Wed, 7 Sep 2016 at 20:53, Craig, Ben via llvm-dev
>     <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>
>         Note that this is intentional from the MSVC C++ library
>         implementation side of things. For major versions, no attempt
>         is made to preserve library ABI compatibility.
>
>         I am aware of a language ABI break in VC++ 2013.
>        
https://randomascii.wordpress.com/2013/12/01/vc-2013-class-layout-change-and-wasted-space/
>
>         I'm not currently aware of any on the VC++ 2015 side of
>         things, but that doesn't mean much.
>
>
>         On 9/7/2016 2:34 PM, Martin O'Riordan via llvm-dev wrote:
>>         Apart from the obvious licencing issues, each time I have
>>         moved from one version of VC++ to another, the big problem I
>>         have had is not specifically the ABI at the register passing,
>>         stack organisation level, but rather the implementation
>>         details of the Standard C++ libraries, and in particular the
>>         STL containers.
>>
>>         While the compiler team puts considerable effort into
>>         maintaining the ABI, the C++ library implementation usually
>>         changes a lot.
>>
>>         Since this is largely in the form of very complex headers
>>         defining templates which in turn cause other helper templates
>>         to be used, it is here that I find things go awry.
>>
>>         So for C++, a function like:
>>
>>         std::list<int> foo();
>>
>>         seems simple enough, but if the caller and the callee are
>>         compiled with different versions, it usually won't work
>>         because of some artefact of the STL implementation tuning
>>         that occurs between versions.  In particular, this impacts
>>         things like using C++ interfaces across DLLs and in
>>         pre-compiled libraries.
>>
>>         I think that the ABI maintenance in this case tends to be for
>>         C and POD compatability, but not for the higher level C++
>>         compatability which is unfortunate and restricts how we can
>>         use C++.
>>
>>         Is it possible that it is this aspect of the version change
>>         that is causing your ABI difficulties?
>>
>>         MartinO
>>
>>
>>         On 7 September 2016 at 20:18, Zachary Turner via llvm-dev
>>         <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>>
>>             Can you elaborate on the abi incompatibility? I thought
>>             there were no breaks
>>             On Wed, Sep 7, 2016 at 7:59 AM James Molloy via cfe-dev
>>             <cfe-dev at lists.llvm.org <mailto:cfe-dev at
lists.llvm.org>>
>>             wrote:
>>
>>                 Hi all,
>>
>>                 Firstly sorry I'm a bit late responding on this
one.
>>                 Internally to ARM we build LLVM for Windows. Our
>>                 current build cluster has only VS2013 installed and
>>                 as a result of this thread we've been working on
>>                 getting VS2015 installed. This involves a certain
>>                 amount of IT-wrangling as the cluster we use is
>>                 company-wide. There have been some hiccups regarding
>>                 licensing of MSVC professional (we can't use the
>>                 community edition for the same reasons mentioned by
>>                 Paul previously) but we hoped to be ready in time for
>>                 the 15th September switchover date.
>>
>>                 It's recently been realised that VS2013 and VS2015
>>                 are not ABI compatible (something that really
>>                 surprised me), and this means we have to synchronize
>>                 moving LLVM's build to VS2015 as well as upgrading
a
>>                 third party library that we receive from the vendor
>>                 in compiled library form. This is not something
we're
>>                 capable of doing by September 15th.
>>
>>                 We try really hard at ARM to hide our internal
>>                 processes because we believe that they're on the
>>                 whole irrelevant to the community, however in this
>>                 case we'd be really stuck, unable to get production
>>                 builds.
>>
>>                 As this is an ABI-incompatible upgrade, and it's
>>                 changing the informal policy on upgrades, could we
>>                 please have some more grace time? Ideally another
>>                 month, so the 15th October. If we haven't sorted it
>>                 by then, it's our problem.
>>
>>                 Cheers,
>>
>>                 James
>>
>>                 On Thu, 1 Sep 2016 at 21:06 Mehdi Amini via cfe-dev
>>                 <cfe-dev at lists.llvm.org
>>                 <mailto:cfe-dev at lists.llvm.org>> wrote:
>>
>>>                     On Sep 1, 2016, at 1:05 PM, Reid Kleckner
>>>                     <rnk at google.com <mailto:rnk at
google.com>> wrote:
>>>
>>>                     On Thu, Sep 1, 2016 at 12:53 PM, Mehdi Amini
via
>>>                     cfe-dev <cfe-dev at lists.llvm.org
>>>                     <mailto:cfe-dev at lists.llvm.org>>
wrote:
>>>
>>>                         Isn’t a big (the most) reason for
supporting
>>>                         “old” toolchains to allow downstream users
>>>                         to upgrade with some flexibility?
>>>                         If I have a large codebase that is using
>>>                         LLVM (let say a few custom backends), and
is
>>>                         validated with “MSVC 2013”, I can upgrade
to
>>>                         “2015” but I will need some
>>>                         qualification/validation: this is not free
>>>                         and take some time. If you drop
aggressively
>>>                         supports for “old” toolchain it means that
>>>                         I’m either stuck with an “old” LLVM or that
>>>                         I have to update earlier than expected.
>>>
>>>                         Isn’t this usually balanced in upstream
LLVM
>>>                         to upgrade when there is a real *benefit*
to
>>>                         it?
>>>                         I’m mentioning it because it seems to
>>>                         conflict with the "always upgrade to
the
>>>                         newest one unless there are serious issues
>>>                         with it” you mentioned above.
>>>
>>>
>>>                     I agree, we should raise the minimum VS version
>>>                     requirement when the benefits to the LLVM
>>>                     community outweigh the costs of switching for
>>>                     major LLVM contributors and users. I think
we'll
>>>                     always make that decision in the same way: by
>>>                     raising it on the mailing lists and discussing
>>>                     the pros and cons. That's basically what
David
>>>                     said when he kicked this whole discussion off,
>>>                     anyway:
>>>
>>>                     """But if we find ourselves in a
situation where
>>>                     asking folks to upgrade to a compiler which has
>>>                     been widely deployed soothes development for
the
>>>                     greater LLVM community, we should consider
>>>                     dropping support for the older versions of that
>>>                     compiler."""
>>>
>>>                     I think everything is working as intended here.
>>
>>                     Right, to be clear there is no misunderstanding:
>>                     I was absolutely not suggesting the opposite when
>>                     answering Zach..
>>
>>                     —
>>                     Mehdi
>>
>>
>>>                     We raised the VS 2013 upgrade issue, discussed
>>>                     it, determined that it was holding us back, and
>>>                     now we're doing the upgrade. If VS
"15" brings
>>>                     major language compatibility improvements, I
>>>                     imagine we'll be having this same
discussion
>>>                     again next year. If it doesn't, and
supporting
>>>                     2015 and "15" at the same time has
the same
>>>                     cost, then we won't bother raising the
floor for
>>>                     a while.
>>
>>                     _______________________________________________
>>                     cfe-dev mailing list
>>                     cfe-dev at lists.llvm.org
>>                     <mailto:cfe-dev at lists.llvm.org>
>>                    
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>>                 _______________________________________________
>>                 cfe-dev mailing list
>>                 cfe-dev at lists.llvm.org <mailto:cfe-dev at
lists.llvm.org>
>>                 http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>>
>>             _______________________________________________
>>             LLVM Developers mailing list
>>             llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
>>             http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>>
>>
>>         _______________________________________________
>>         LLVM Developers mailing list
>>         llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
>>         http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>         -- 
>         Employee of Qualcomm Innovation Center, Inc.
>         Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
>
>         _______________________________________________
>         LLVM Developers mailing list
>         llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
>         http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>     _______________________________________________
>     LLVM Developers mailing list
>     llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>     http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project

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