[Buildroot] host gcc?

[Buildroot] host gcc?

[Kennedy, Andy A Collins via buildroot]

Many years ago, I recall (perhaps erroneously) that the toolchain build
also required building an intermediate gcc to get to the latest version
of the selected toolchain.  I now require selecting options that need a
toolchain that is older than the version of gcc I'm stuck using (for
reasons I won't address here).  Specifically, I'm attempting to select
BR2_PACKAGE_PYTHON_SCIPY which has a dependency of
BR2_HOST_GCC_AT_LEAST_9 and BR2_TOOLCHAIN_HAS_FORTRAN, the latter of
which is easy to overcome by configuration.  The former, however, is
what stumps me.  I need to provide a gcc that is greater than the much
older version than gcc-9.

Do I have an easy path to this goal?  Assuming the answer is no, would
there be support in providing a way to select the current toolchain
gcc build as a host to host compiler at the same time?

It is good to be back!  I've been missing from BuildRoot for many years.

Andy
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Re: [Buildroot] host gcc?

[Arnout Vandecappelle via buildroot]

  Hi Andy,

On 26/06/2024 23:02, Kennedy, Andy A Collins via buildroot wrote:
> Many years ago, I recall (perhaps erroneously) that the toolchain build
> also required building an intermediate gcc to get to the latest version
> of the selected toolchain.

  We still have that: package/gcc/gcc-initial.

  It's not a host gcc though, it's for the target. We need to build it to be 
able to build the standard library, and we then need to build the final gcc 
using that standard library.

>  I now require selecting options that need a
> toolchain that is older than the version of gcc I'm stuck using (for
> reasons I won't address here).  Specifically, I'm attempting to select
> BR2_PACKAGE_PYTHON_SCIPY which has a dependency of
> BR2_HOST_GCC_AT_LEAST_9 and BR2_TOOLCHAIN_HAS_FORTRAN, the latter of
> which is easy to overcome by configuration.  The former, however, is
> what stumps me.  I need to provide a gcc that is greater than the much
> older version than gcc-9.
> 
> Do I have an easy path to this goal?

  The relatively easy path is to build GCC 9 outside of buildroot, and specify 
it by passing HOSTCC and HOSTCXX in the environment. Or making sure that GCC 9's 
installation dir is earlier in PATH.

>  Assuming the answer is no, would
> there be support in providing a way to select the current toolchain
> gcc build as a host to host compiler at the same time?

  Sounds like a valid idea, but it's not so simple to implement, because it 
means that HOSTCC has to change somewhere in the middle of the build...

  Also, it's probably better to stick to a single GCC version, and make sure it 
can be used regardless of whether an internal or external toolchain is used.

  Regards,
  Arnout

> 
> It is good to be back!  I've been missing from BuildRoot for many years.
> 
> Andy
> _______________________________________________
> buildroot mailing list
> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot
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Re: [Buildroot] [External] Re: host gcc?

[Kennedy, Andy A Collins via buildroot]

On 30/06/2024 09:25, Vandercappelle, Arnout via buildroot wrote:
>   Hi Andy,
>
> On 26/06/2024 23:02, Kennedy, Andy A Collins via buildroot wrote:
> > Many years ago, I recall (perhaps erroneously) that the toolchain build
> > also required building an intermediate gcc to get to the latest version
> > of the selected toolchain.
>
>   We still have that: package/gcc/gcc-initial.
>
>   It's not a host gcc though, it's for the target. We need to build it to be
> able to build the standard library, and we then need to build the final gcc
> using that standard library.

Per the below comment, it makes me think I didn't articulate correctly:
I need gcc >9 for scipy on the HOST.  The package builds for the HOST
and for TARGET (for which I'm using gcc12+, so I'm good there), but I
also need to match the HOST gcc>9 requirement --- which, it is not.
Hmmm, so I may be able to make the intermediate stuff work easily if I
were to change the requirement of BuildRoot to be a higher version...
You may have given me the easier path.  THANK YOU!!!

>
> >  I now require selecting options that need a
> > toolchain that is older than the version of gcc I'm stuck using (for
> > reasons I won't address here).  Specifically, I'm attempting to select
> > BR2_PACKAGE_PYTHON_SCIPY which has a dependency of
> > BR2_HOST_GCC_AT_LEAST_9 and BR2_TOOLCHAIN_HAS_FORTRAN, the
> > latter of
> > which is easy to overcome by configuration.  The former, however, is
> > what stumps me.  I need to provide a gcc that is greater than the much
> > older version than gcc-9.
> >
> > Do I have an easy path to this goal?
>
>   The relatively easy path is to build GCC 9 outside of buildroot, and specify
> it by passing HOSTCC and HOSTCXX in the environment. Or making sure that
> GCC 9's
> installation dir is earlier in PATH.

I have to do this inside BuildRoot as I'm not root.

>
> >  Assuming the answer is no, would
> > there be support in providing a way to select the current toolchain
> > gcc build as a host to host compiler at the same time?
>
>   Sounds like a valid idea, but it's not so simple to implement, because it
> means that HOSTCC has to change somewhere in the middle of the build...
>
>   Also, it's probably better to stick to a single GCC version, and make sure it
> can be used regardless of whether an internal or external toolchain is used.
>
>   Regards,
>   Arnout
>
Thanks for the reply, I think this gets me there!

Andy
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Re: [Buildroot] [External] Re: host gcc?

[Yann E. MORIN]

Andy, All,

On 2024-07-01 20:07 +0000, Kennedy, Andy A Collins via buildroot spake thusly:
> On 30/06/2024 09:25, Vandercappelle, Arnout via buildroot wrote:
[--SNIP--]
> >   The relatively easy path is to build GCC 9 outside of buildroot, and specify
> > it by passing HOSTCC and HOSTCXX in the environment. Or making sure that
> > GCC 9's
> > installation dir is earlier in PATH.
> I have to do this inside BuildRoot as I'm not root.

You don't need to be root; just install it anywhere you have access to,
line ${HOME}/gcc-9/  and export that in the PATH.

Alternatively, build in a container runing a distribution with a more
recent compiler suite.

Regards,
Yann E. MORIN.

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Re: [Buildroot] [External] Re: host gcc?

[Kennedy, Andy A Collins via buildroot]

On 01/07/2024 16:07, Yann Morin via buildroot wrote:
> Andy, All,
>
> On 2024-07-01 20:07 +0000, Kennedy, Andy A Collins via buildroot spake
> thusly:
> > On 30/06/2024 09:25, Vandercappelle, Arnout via buildroot wrote:
> [--SNIP--]
> > >   The relatively easy path is to build GCC 9 outside of buildroot, and specify
> > > it by passing HOSTCC and HOSTCXX in the environment. Or making sure
> that
> > > GCC 9's
> > > installation dir is earlier in PATH.
> > I have to do this inside BuildRoot as I'm not root.
>
> You don't need to be root; just install it anywhere you have access to,
> line ${HOME}/gcc-9/  and export that in the PATH.
>
> Alternatively, build in a container runing a distribution with a more
> recent compiler suite.

I don't know the machine.  I don't know the user.  It has to be BR.

I could do a script to build a local gcc...  that's worse.

Andy
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