Re: native builds

["Yann E. MORIN" <yann dot morin dot 1998 at anciens dot enib dot fr>]

Roland,
All,

On Friday 27 February 2009 17:42:35 Roland Schwarz wrote:
> I forgot to mention I am talking about toolset-ng scripts.

toolset-ng? I don't know about this...
Are you speaking of crosstool-NG?

> I am using the
> ct-ng menuconfig

Yes, seems you are using crosstool-ng... ;-)

> front-end which ends up in a configuration variable:
> CT_TOOLCHAIN_TYPE="native"
> The feature (native builds) is marked "experimental" and
> "no code". So I am just wondering if this indicates that
> the code just has not yet been written.

First, it's under EXPERIMENTAL, so that the user really knows he/she
is trying experimental features.

Second, it's marked as NO CODE because there is actually no code to
build a "native" toolchain. The only code present detects this and
bails out.

So, in the state, it will not work.

> Then I am unsure if I need a "cross-compiler" or a "native-compiler"
> for my case. Basically I want to set up several compilers that
> are able to target several versions of linux & several versions
> of glibc while running on the same host.

First:
What are you refering to by "running on the same host"?
Are you saying the _compilers_ are to run on the same machine?
Or do you mean that the compilers should _produce_ code that run on the
same machine?

Second:
What do you mean by "on the same host"?
Are you saying that the machine the compilers produce code for is the
same machine as the compilers run on?

> Is it possible to have "build==host!=target" where target
> only differs in glibc/linux-headers ?

I guess you mean "differ in glibc and/or linux-headers version". This is
what crosstool-NG calls a native compiler, and is not (yet) supported, as
I do not have a need for it yet (but will in the future). However, I have
no timeline.

> Would I even need a cross compiler?

You could work this around using the "Vendor string" option (in the menu
"Toolchain options"), and set it to something different from your host's
tuple. Then you'd build a cross-compiler.

Say you are running under i686-pc-linux-gnu, then you could set the vendor
string to "rs_pc" which would give i686-rs_pc-linux-gnu. This is untested,
and you might end up with gcc having problems differentiating headers for
the host from headers for the target.

(In the spirit of crosstool-NG, a "native" compiler whould be able to install
 in /, and be used as a replacement for the existing compiler. This raises a
 few interesting points, such as headers and library search paths, run-time
 paths, and so on...)

Regards,
Yann E. MORIN.

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