[Buildroot] Disabling Synopsys ARC pre-built toolchains in Buildroot

[Waldemar Brodkorb <wbx@openadk.org>]

Hi Alexey,
Alexey Brodkin wrote,

> Hi Thomas,
> 
> On Fri, 2015-04-17 at 21:47 +0200, Arnout Vandecappelle wrote:
> > On 17/04/15 10:49, Alexey Brodkin wrote:
> > >  [1] Buildroot defconfigs for uClibc are not generated by "make
> > > savedefconfig" which makes it very hard to understand which options are
> > > enabled and which are disabled compared to defaults.
> > 
> >  I think the only reason why this is the case is that uClibc didn't use to
> > support savedefconfig. AFAICS 0.9.33.2 still doesn't.
> > 
> > 
> > >  [2] Buildroot defconfig may contain options (disabled or enabled
> > > compared to defaults) that might be harmful (in run-time issues like
> > > performance degradation etc). Remember missing
> > > UCLIBC_HAS_STRING_GENERIC_OPT. This is I think a reminder of early days
> > > of Buildroot. And so blind use of Buildroot defconfig as defconfig for
> > > ARC might not work well enough.
> > 
> >  We're certainly open to improving the BR defconfigs!
> 
> Please note that we added missing options:
>  * UCLIBC_HAS_UTMP=y
>  * UCLIBC_HAS_UTMPX=y
>  * UCLIBC_HAS_LIBUTIL=y
>  * UCLIBC_USE_NETLINK=y
>  * UCLIBC_SUPPORT_AI_ADDRCONFIG=y
>  * UCLIBC_HAS_LIBNSL_STUB=y
> 
> in uClibc defconfigs for ARC so the next release of ARC toolchain will have them -
> https://github.com/foss-for-synopsys-dwc-arc-processors/uClibc/commit/ab87ede75f9b9b837d579c8eeef3ab4f22fd45d1
> 
> As for remaining differences between Buildroot and ARC uClibc defconfigs
> these are ones I may see (comparing
> https://github.com/foss-for-synopsys-dwc-arc-processors/uClibc/blob/arc-mainline-dev/extra/Configs/defconfigs/arc/defconfig with "uClibc-snapshot.config" from http://patchwork.ozlabs.org/patch/462812/):
> 
>  [1] MALLOC_GLIBC_COMPAT=y
>  [2] UCLIBC_HAS_GETPT=y
>  [3] UCLIBC_HAS_CTYPE_CHECKED=y
>  [4] UCLIBC_HAS_HEXADECIMAL_FLOATS=y
>  [5] UCLIBC_HAS_GLIBC_CUSTOM_PRINTF=y
>  [6] UCLIBC_HAS_FOPEN_EXCLUSIVE_MODE=y
>  [7] UCLIBC_HAS_PRINTF_M_SPEC=y
>  [8] UCLIBC_HAS_SSP=y
>  [9] UCLIBC_BUILD_NOW=y
> 
> Do you think some of them are really important and we may want to add
> them in ARC defconfigs?

I think MALLOC_GLIBC_COMPAT should be enabled. GNU libc and musl
behaves in the same way, only uClibc does it another way.
uClibc-ng-master already removed this option, because it will be the
default for the next major release.

best regards
 Waldemar