[lttng-dev] [lttng-tools] build failure on armel (debian)

[Mathieu Desnoyers]

This is very likely caused by a configuration issue with your
userspace RCU library, or by a configuration issue with your
lttng-tools (at the very least, a discrepancy between the two).

If we look at urcu:

urcu/arch/arm.h:

#ifdef CONFIG_RCU_ARM_HAVE_DMB
#define cmm_mb()        __asm__ __volatile__ ("dmb":::"memory")
#define cmm_rmb()       __asm__ __volatile__ ("dmb":::"memory")
#define cmm_wmb()       __asm__ __volatile__ ("dmb":::"memory")
#endif /* CONFIG_RCU_ARM_HAVE_DMB */

you probably have this config option defined by the config.h
generated by urcu. This is probably a discrepancy between your
urcu configuration and the compiler target used when building
lttng-tools.

Thoughts ?

Thanks,

Mathieu

----- Original Message -----
> From: "Jon Bernard" <jbernard at debian.org>
> To: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> Cc: lttng-dev at lists.lttng.org
> Sent: Tuesday, May 20, 2014 3:15:57 PM
> Subject: Re: [lttng-dev] [lttng-tools] build failure on armel (debian)
> 
> * Mathieu Desnoyers <mathieu.desnoyers at efficios.com> wrote:
> > ----- Original Message -----
> > > From: "Jon Bernard" <jbernard at debian.org>
> > > To: lttng-dev at lists.lttng.org
> > > Sent: Tuesday, May 6, 2014 11:14:03 AM
> > > Subject: [lttng-dev] [lttng-tools] build failure on armel (debian)
> > > 
> > > Hey guys,
> > > 
> > > This bug¹ was filed recently:
> > > 
> > >     your package no longer builds on the armel buildds:
> > >     https://buildd.debian.org/status/fetch.php?pkg=ltt-control&arch=armel&ver=2.4.1-1&stamp=1397064419
> > > 
> > >     >   CC       rculfhash.lo
> > >     > /tmp/ccBG89vh.s: Assembler messages:
> > >     > /tmp/ccBG89vh.s:1105: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:1286: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:3175: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:3725: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:3833: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:3994: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:4331: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > /tmp/ccBG89vh.s:5292: Error: selected processor does not support
> > >     > ARM
> > >     > mode `dmb'
> > >     > make[4]: *** [rculfhash.lo] Error 1
> > > 
> > > The public buildd that I can use to test this is unreachable at the
> > > moment, but maybe a solution can be reached without further debug info?
> > > 
> > > The build machine is ARMv7, which supports dmb IIUC, so I'm a bit
> > > puzzled on this one.
> > > 
> > > Any thoughts?
> > 
> > Perhaps the build itself has been changed to target ARMv6 ?
> > 
> > Starting with ARMv7, dmb should be there.
> > 
> > For ARMv6 support (and less), the Linux kernel provides
> > a vDSO page implementing __kuser_memory_barrier. If you
> > really need to build for ARMv6, this might be something
> > to look into.
> > 
> > I guess we'll need more information about your build
> > target.
> 
> Here is a full build log: http://sprunge.us/FIJe
> 
> Build occurred on this machine:
> 
>     Linux abel 3.13-1-armmp-lpae #4 SMP Thu Mar 27 16:56:17 UTC 2014 armv7l
>     GNU/Linux
> 
> Is there anything else I should include?
> 
> --
> Jon
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com