openmp in gcc-cross

openmp in gcc-cross

[Phil Blundell]

At present gcc-4.2.4.inc sets:

EXTRA_OECONF_BASE = "--enable-libssp --disable-bootstrap --disable-libgomp --disable-libmudflap"

There doesn't seem to be any good reason to disable libgomp, and its
absence is breaking gettext-0.16.1 at least.  Does anybody know why it
was disabled, and/or know a good reason why it shouldn't be re-enabled?

p.

Re: openmp in gcc-cross

[Koen Kooi]

Phil Blundell wrote:
> At present gcc-4.2.4.inc sets:
>
> EXTRA_OECONF_BASE = "--enable-libssp --disable-bootstrap --disable-libgomp --disable-libmudflap"
>
> There doesn't seem to be any good reason to disable libgomp, and its
> absence is breaking gettext-0.16.1 at least.  Does anybody know why it
> was disabled, and/or know a good reason why it shouldn't be re-enabled?

It broke builds for some people (but not all).

regards,

Koen

Re: openmp in gcc-cross

[Phil Blundell]

On Tue, 2008-08-05 at 12:35 +0200, Koen Kooi wrote:
> It broke builds for some people (but not all).

What was the breakage?  It seems like it would be a better idea to fix
that than just to disable it.

p.

Re: openmp in gcc-cross

[Koen Kooi]

Phil Blundell wrote:
> On Tue, 2008-08-05 at 12:35 +0200, Koen Kooi wrote:
>> It broke builds for some people (but not all).
>
> What was the breakage?  It seems like it would be a better idea to fix
> that than just to disable it.

I wasn't one of the people seeing the breakage, so I'll leave it to the 
people that reported to respond.

regards,

Koen

Re: openmp in gcc-cross

[Khem Raj]

I also saw the error long back on arm I dont remember the error
anymore. This was with gcc 4.2.1 or some such. You can enable it may
be it builds now its been long. Open MP on an embedded system might be
overkill. What is the error you are getting ? Can gettext build
without libgomp. How will it compile with older compilers ?

Thanks

-Khem

On Tue, Aug 5, 2008 at 5:26 AM, Koen Kooi <k.kooi@student.utwente.nl> wrote:
> Phil Blundell wrote:
>>
>> On Tue, 2008-08-05 at 12:35 +0200, Koen Kooi wrote:
>>>
>>> It broke builds for some people (but not all).
>>
>> What was the breakage?  It seems like it would be a better idea to fix
>> that than just to disable it.
>
> I wasn't one of the people seeing the breakage, so I'll leave it to the
> people that reported to respond.
>
> regards,
>
> Koen
>
>
> _______________________________________________
> Openembedded-devel mailing list
> Openembedded-devel@lists.openembedded.org
> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel
>

Re: openmp in gcc-cross

[Phil Blundell]

The error with gettext is just a straightforward "-lgomp not found" kind
of thing.  Gettext will compile OK with older, non-OpenMP-capable
compilers: it checks for the -fopenmp flag during configure, but it
expects (not unreasonably) that if you have an OpenMP capable compiler
then you will also have the right libraries available.

For people who don't want OpenMP I think the right thing is to have a
global "USE_OPENMP" variable to turn off OpenMP support at the package
level.  For most autotools-using packages this is going to mean adding
"--disable-openmp" to EXTRA_OECONF.

You're right that OpenMP might indeed be overkill on some/most embedded
systems, but embedded multi-threading is by no means unheard of and I
guess it will become more popular as CPUs like the Cortex-A9 and newer
Pentiums start to show up in these systems.

I verified that libgomp does compile OK with gcc 4.2.2, so I guess I'll
go ahead and re-enable it for that version at least.

p.

On Tue, 2008-08-05 at 17:57 -0700, Khem Raj wrote:
> I also saw the error long back on arm I dont remember the error
> anymore. This was with gcc 4.2.1 or some such. You can enable it may
> be it builds now its been long. Open MP on an embedded system might be
> overkill. What is the error you are getting ? Can gettext build
> without libgomp. How will it compile with older compilers ?
> 
> Thanks
> 
> -Khem
> 
> On Tue, Aug 5, 2008 at 5:26 AM, Koen Kooi <k.kooi@student.utwente.nl> wrote:
> > Phil Blundell wrote:
> >>
> >> On Tue, 2008-08-05 at 12:35 +0200, Koen Kooi wrote:
> >>>
> >>> It broke builds for some people (but not all).
> >>
> >> What was the breakage?  It seems like it would be a better idea to fix
> >> that than just to disable it.
> >
> > I wasn't one of the people seeing the breakage, so I'll leave it to the
> > people that reported to respond.
> >
> > regards,
> >
> > Koen
> >
> >
> > _______________________________________________
> > Openembedded-devel mailing list
> > Openembedded-devel@lists.openembedded.org
> > http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel
> >
> 
> _______________________________________________
> Openembedded-devel mailing list
> Openembedded-devel@lists.openembedded.org
> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel

Re: openmp in gcc-cross

[Koen Kooi]

Phil Blundell wrote:
> The error with gettext is just a straightforward "-lgomp not found" kind
> of thing.  Gettext will compile OK with older, non-OpenMP-capable
> compilers: it checks for the -fopenmp flag during configure, but it
> expects (not unreasonably) that if you have an OpenMP capable compiler
> then you will also have the right libraries available.
>
> For people who don't want OpenMP I think the right thing is to have a
> global "USE_OPENMP" variable to turn off OpenMP support at the package
> level.  For most autotools-using packages this is going to mean adding
> "--disable-openmp" to EXTRA_OECONF.
>
> You're right that OpenMP might indeed be overkill on some/most embedded
> systems, but embedded multi-threading is by no means unheard of and I
> guess it will become more popular as CPUs like the Cortex-A9 and newer
> Pentiums start to show up in these systems.

Speaking of cortex-A9 MPCore (and arm11 MPCore as well), how well does 
linux (kernel + c library) support MP on arm? I heard horror stories 
about missing memory barriers, but that was over a year ago.

> I verified that libgomp does compile OK with gcc 4.2.2, so I guess I'll
> go ahead and re-enable it for that version at least.

gcc 4.2.4 (re)built fine for me after your latest changes.

regards,

Koen