RE: How to enable GLIBCXX & CXXABI in yocto

[WENG Binyang <binyang.weng@forvia.com>]

Thanks a lot!

> -----Original Message-----
> From: Jonathan Wakely <jwakely.gcc@gmail.com>
> Sent: Wednesday, April 27, 2022 5:27 PM
> To: WENG Binyang <binyang.weng@forvia.com>
> Cc: gcc-help@gcc.gnu.org
> Subject: Re: How to enable GLIBCXX & CXXABI in yocto
> 
> On Wed, 27 Apr 2022 at 07:30, WENG Binyang <binyang.weng@forvia.com>
> wrote:
> >
> > Hi gcc-help team,
> >
> > I am working on create a arm toolchain by yocto.
> > I confirmed the generated toolchain, but found no GLIBCXX_3.* and CXXABI
> in libstdc++ for arm64. Please refer to the following.
> >
> >
> xxx:~/Workspace/EMIRROR/sdk/linux/yocto-build/toolchain/sysroots/aarch
> > 64-linux/usr/lib$ strings libstdc++.so.6.0.28 | grep GLIBCXX
> > GLIBCXX_FORCE_NEW GLIBCXX_DEBUG_MESSAGE_LENGTH
> >
> > Could you tell me how to enable GLIBCXX_3* and CXXABI in yocto build?
> 
> It depends on linker support and the value of the --enable-symvers configure
> option.
> 
> See https://gcc.gnu.org/onlinedocs/libstdc++/manual/configure.html
> 
> --enable-symvers[=style]
> 
> In 3.1 and later, tries to turn on symbol versioning in the shared library (if a
> shared library has been requested). Values for 'style'
> that are currently supported are 'gnu', 'gnu-versioned-namespace', 'darwin',
> 'darwin-export', and 'sun'. Both gnu- options require that a recent version of
> the GNU linker be in use. Both darwin options are equivalent. With no style
> given, the configure script will try to guess correct defaults for the host system,
> probe to see if additional requirements are necessary and present for
> activation, and if so, will turn symbol versioning on. This option can change the
> library ABI.
> 
> And the comments in libstdc++-v3/acinclude.m4
> 
> dnl
> dnl Add version tags to symbols in shared library (or not), additionally dnl
> marking other symbols as private/local (or not).
> dnl
> dnl Sets libtool_VERSION, and determines shared library SONAME.
> dnl
> dnl  This depends on GLIBCXX CHECK_LINKER_FEATURES, but without it
> assumes no.
> dnl
> dnl --enable-symvers=style adds a version script to the linker call when
> dnl       creating the shared library.  The choice of version script is
> dnl       controlled by 'style'.
> dnl --disable-symvers does not.
> dnl
> dnl  +  Usage:  GLIBCXX_ENABLE_SYMVERS[(DEFAULT)]
> dnl       Where DEFAULT is either 'yes' or 'no'.  Passing `yes' tries to
> dnl       choose a default style based on linker characteristics.  Passing
> dnl       'no' disables versioning.
> dnl

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