[Gc] libatomic-ops-7.4.0 not compatible with ppc64le architecture

Deepak C Shetty deepakcs at linux.vnet.ibm.com
Sun Dec 22 22:12:13 PST 2013


Lennart,
     Thanks for your response. I too am not an expert of this area to help.

I have fwd.ded this mail to an internal list, its possible
someone might contact you or mail you or if they comeback to me.. I can 
get you connected
with the IBM person that can look at it.

thanx,
deepak

On 12/20/2013 08:18 PM, Lennart Sorensen wrote:
> On Fri, Dec 20, 2013 at 09:44:38AM -0500, Lennart Sorensen wrote:
>> On Fri, Dec 20, 2013 at 10:48:14AM +0530, Deepak C Shetty wrote:
>>> On 12/19/2013 03:27 AM, Lennart Sorensen wrote:
>>>> On Wed, Dec 18, 2013 at 04:30:54PM +0530, Madhu Pavan wrote:
>>>>> Hi Ivan Maidanski,
>>>>>
>>>>> We are in the process of adding support for new arch (ppc64le) and
>>>>> as part of that we wanted to send patches for config.guess and
>>>>> configure as appropriate.
>>>>>
>>>>> libatomic-ops-7.4.0 could not be built on ppc64le because it had an
>>>>> outdated configure/config.guess/libtool.m4. Since your pkg uses
>>>>> libtool and the latest tarball of your pkg didn't build on ppc64le
>>>>> due to outdated libtool present on your system. We wanted to request
>>>>> you to upgrade your libtool to the alpha release of libtool which
>>>>> has all the bits and pieces needed for ppc64le support.
>>>>>
>>>>> In that context, I wanted to confirm the below
>>>>>
>>>>> 1) Should we send patches to 'gc at linux.hpl.hp.com' mailing list or
>>>>> there is some other mailing list ?
>>>>>
>>>>> 2) New libtool alpha release which supports ppc64le arch is
>>>>> available, you may  pick up the alpha release from either of the
>>>>> below :
>>>>>
>>>>> ftp://alpha.gnu.org/gnu/libtool/libtool-2.4.2.418.tar.gz (1.6MB)
>>>>>
>>>>> ftp://alpha.gnu.org/gnu/libtool/libtool-2.4.2.418.tar.xz (920KB)
>>>>>
>>>>> It would be great if you can install this new libtool which supports
>>>>> ppc64le, and spin the pkg and let us know the new tar availability.
>>>>> We can test it on ppc64le architecture for you. Please let me know
>>>>> if you are planning to release or spin newer version.
>>>>>
>>>>> Currently I used
>>>>>
>>>>> https://www.hpl.hp.com/research/linux/atomic_ops/download.php4
>>>>>
>>>>> Which does not have ppc64le support.
>>>>>
>>>>> Your response is highly appreciated.
>>>> Well in my experience libatomic-ops doesn't work at all on powerpc,
>>>> at least if run on a power7.  The testsuite fails.  It seems to somehow
>>>> get by on power6 and older.  Many things have had bugs exposed by power7
>>>> since it seems the power7 really relies on the memory model rules of
>>>> the power architecture in ways previous designs did not.  Use of memory
>>>> barriers have to be done correctly to work on the power7, otherwise
>>>> different CPUs will often see different values in memory due to caching.
>>> Hi Lennart,
>>>      Thanks for letting us know. We were not aware of it.
>>>
>>> Would you know if someone from community/IBM is looking/working on
>>> this and/or there is any effort to get this working on Power7
>>> systems ?
>> I am not aware of anyone working on it.  I looked at it, but it is beyond
>> my skill set at this time.  I think given the complexity of doing atomic
>> ops safely on a multi cpu system, it might need the help of someone at
>> IBM that really knows the architecture.
>>
>> I just know about it because we have a power6 and a power7 IBM system
>> we run Debian on as a build system, and pixman failed the testsuite on
>> the power7, but passed on the power6.
>>
>> I have been tempted to "fix" the problem by just putting locks in place
>> and not caring that it completely defeats the purpose of the library.
>> At least it would work.
> If anyone is interested I can provide the output of a few runs (it does
> not fail the same way every time, given it is multithreaded and all
> and breaking things),  Sometimes it fails with duplicate entries in the
> stack test, and other times it gets into and infinite loop because it
> has managed to make an entry's next point at itself.
>
> I am happy to test patches too.
>



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