uclibc: proper thread default on m68k and Microblaze

Traditionally, Buildroot has a default of enabling thread
support. However, with the current construct of the thread choice in the
uclibc package, the m68k and microblaze architecture end up with no
thread support as the default.

In order to avoid having to explicit a more complicated "default" value
for the choice, we take a simple approach:

 - The "none" choice is moved at the end of the list, so that it is not
   selected as the default unless there is really no other thread
   implementation available.

 - We make NPTL the default thread implementation.

 - On architectures where NPTL is not available, the NPTL option will
   not be available, so Kconfig will automatically fallback to
   linuxthreads.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 package/uclibc/Config.in | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Hi,
Thomas Petazzoni wrote,

> Traditionally, Buildroot has a default of enabling thread
> support. However, with the current construct of the thread choice in the
> uclibc package, the m68k and microblaze architecture end up with no
> thread support as the default.
> 
> In order to avoid having to explicit a more complicated "default" value
> for the choice, we take a simple approach:
> 
>  - The "none" choice is moved at the end of the list, so that it is not
>    selected as the default unless there is really no other thread
>    implementation available.
> 
>  - We make NPTL the default thread implementation.
> 
>  - On architectures where NPTL is not available, the NPTL option will
>    not be available, so Kconfig will automatically fallback to
>    linuxthreads.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Makes sense to me.
You can add:
Reviewed-by: Waldemar Brodkorb <wbx@openadk.org>

best regards
 Waldemar

Thomas, All,

On 2016-08-05 18:35 +0200, Thomas Petazzoni spake thusly:
> Traditionally, Buildroot has a default of enabling thread
> support. However, with the current construct of the thread choice in the
> uclibc package, the m68k and microblaze architecture end up with no
> thread support as the default.
> 
> In order to avoid having to explicit a more complicated "default" value
> for the choice, we take a simple approach:
> 
>  - The "none" choice is moved at the end of the list, so that it is not
>    selected as the default unless there is really no other thread
>    implementation available.
> 
>  - We make NPTL the default thread implementation.
> 
>  - On architectures where NPTL is not available, the NPTL option will
>    not be available, so Kconfig will automatically fallback to
>    linuxthreads.

And to make things even more simple, why not move NPTL first, then LT,
then none, and remove the default?

Thus, when NPTL is avbailable, it is used; if not, LT is used; if not,
then none is used.

Regards,
Yann E. MORIN.

> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  package/uclibc/Config.in | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/package/uclibc/Config.in b/package/uclibc/Config.in
> index 7c99195..b7714d4 100644
> --- a/package/uclibc/Config.in
> +++ b/package/uclibc/Config.in
> @@ -47,15 +47,13 @@ config BR2_TOOLCHAIN_BUILDROOT_LOCALE
>  
>  choice
>  	prompt "Thread library implementation"
> +	# Use NPTL when available. If not available, kconfig will
> +	# automatically fall back to linuxthreads.
>  	default BR2_PTHREADS_NATIVE
> -	default BR2_PTHREADS if !BR2_USE_MMU
>  	help
>  	  Use this option to select the thread library implementation
>  	  that should be used in your toolchain.
>  
> -	config BR2_PTHREADS_NONE
> -		bool "none"
> -
>  	config BR2_PTHREADS
>  		bool "linuxthreads"
>  		select BR2_TOOLCHAIN_HAS_THREADS
> @@ -67,6 +65,10 @@ choice
>  		select BR2_TOOLCHAIN_HAS_THREADS_NPTL
>  		depends on BR2_USE_MMU
>  		depends on !BR2_m68k && !BR2_microblaze
> +
> +	config BR2_PTHREADS_NONE
> +		bool "none"
> +
>  endchoice
>  
>  config BR2_PTHREAD_DEBUG
> -- 
> 2.7.4
> 
> _______________________________________________
> buildroot mailing list
> buildroot@busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

Hello,

On Sun, 7 Aug 2016 22:15:52 +0200, Yann E. MORIN wrote:

> And to make things even more simple, why not move NPTL first, then LT,
> then none, and remove the default?

Correct, I've changed the patch with this idea and applied. Thanks for
the suggestion!

Thomas

Hello,

On Fri,  5 Aug 2016 18:35:41 +0200, Thomas Petazzoni wrote:
> Traditionally, Buildroot has a default of enabling thread
> support. However, with the current construct of the thread choice in the
> uclibc package, the m68k and microblaze architecture end up with no
> thread support as the default.
> 
> In order to avoid having to explicit a more complicated "default" value
> for the choice, we take a simple approach:
> 
>  - The "none" choice is moved at the end of the list, so that it is not
>    selected as the default unless there is really no other thread
>    implementation available.
> 
>  - We make NPTL the default thread implementation.
> 
>  - On architectures where NPTL is not available, the NPTL option will
>    not be available, so Kconfig will automatically fallback to
>    linuxthreads.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  package/uclibc/Config.in | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

Applied to master, after taking into account Yann's comment.

Thomas