[Buildroot] Knowing whether the target is multicore

[Buildroot] Knowing whether the target is multicore

[Frank Hunleth]

From what I can tell, the answer is no, but I was wondering if there
was any way of knowing in a package's .mk file whether the target is
single or multicore.

The reason that I'm asking is that I'm currently working with the
Erlang package. The Erlang configure script can be told whether to
build a VM that supports multi-core or not. By default, it builds VMs
for both cases. This works, but takes quite a bit longer to compile
and adds to the target image size. I'd like to be able to set this
appropriately, and it seems like this would be better accomplished
using an arch-specific BR2_ variable rather than something in the
Erlang package's Config.in.

Thanks,
Frank

[Buildroot] Knowing whether the target is multicore

[Baruch Siach]

Hi Frank,

On Tue, Dec 10, 2013 at 04:55:37PM -0500, Frank Hunleth wrote:
> From what I can tell, the answer is no, but I was wondering if there
> was any way of knowing in a package's .mk file whether the target is
> single or multicore.
> 
> The reason that I'm asking is that I'm currently working with the
> Erlang package. The Erlang configure script can be told whether to
> build a VM that supports multi-core or not. By default, it builds VMs
> for both cases. This works, but takes quite a bit longer to compile
> and adds to the target image size. I'd like to be able to set this
> appropriately, and it seems like this would be better accomplished
> using an arch-specific BR2_ variable rather than something in the
> Erlang package's Config.in.

Whether a target is SMP or not depends on architecture and kernel 
configuration, and that might be outside of Buildroot control when not 
building the kernel internally. In my opinion, there should be a config option 
allowing the user to select the SMP version or the UP one (or both).

baruch

-- 
     http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

[Buildroot] Knowing whether the target is multicore

[Frank Hunleth]

Hi Baruch,

On Wed, Dec 11, 2013 at 12:35 AM, Baruch Siach <baruch@tkos.co.il> wrote:
> Hi Frank,
>
> On Tue, Dec 10, 2013 at 04:55:37PM -0500, Frank Hunleth wrote:
>> From what I can tell, the answer is no, but I was wondering if there
>> was any way of knowing in a package's .mk file whether the target is
>> single or multicore.
>>
>> The reason that I'm asking is that I'm currently working with the
>> Erlang package. The Erlang configure script can be told whether to
>> build a VM that supports multi-core or not. By default, it builds VMs
>> for both cases. This works, but takes quite a bit longer to compile
>> and adds to the target image size. I'd like to be able to set this
>> appropriately, and it seems like this would be better accomplished
>> using an arch-specific BR2_ variable rather than something in the
>> Erlang package's Config.in.
>
> Whether a target is SMP or not depends on architecture and kernel
> configuration, and that might be outside of Buildroot control when not
> building the kernel internally. In my opinion, there should be a config option
> allowing the user to select the SMP version or the UP one (or both).

Makes sense. Thanks.

Frank

[Buildroot] Knowing whether the target is multicore

[Thomas Petazzoni]

Dear Baruch Siach,

On Wed, 11 Dec 2013 07:35:20 +0200, Baruch Siach wrote:

> Whether a target is SMP or not depends on architecture and kernel 
> configuration, and that might be outside of Buildroot control when not 
> building the kernel internally. In my opinion, there should be a config option 
> allowing the user to select the SMP version or the UP one (or both).

I agree with Baruch: for now, we don't have many packages (if any other
than the one Frank is talking about) that need to know whether the
target will be UP or SMP. Therefore, I would suggest to have an Erlang
specific option to select this behavior.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com