Re: Some fundamental questions for cross too chain.

[Dan Kegel <dank at kegel dot com>]

Tushar wrote:
> I am new to building cross tool chain so please forgive if answer of
> below questions are obvious. (They may be obvious to u) 
>
> I am building a cross tool chain for ARM XSCALE IXP425.
> build=i686-pc-linux-gnu host=i686-pc-linux-gnu
> target=armbe-xscale-linux-gnu. At many place on web I have seen
> procedure as follows,
>
> 1.Compile and install binutil for target
> 2.Configure kernel to generate header and copy arch-specific header to
> prefix dir.
> 3.Compile gcc for target (First pass)
> 4.Cross Compile glibc with above tools and install.
> 5.Compile gcc for target (Second Pass).

Right.  That's the sequence that is automated by
  http://kegel.com/crosstool
I highly recommend using crosstool if you can; it takes
a lot of the pain out of building toolchains.

> First,
> 	Is it necessary to compile gcc twice and if yes why? I can somewhat
> understand if we are building cross compiler where build and host are
> different. But I am not able to understand above steps where build
> machine and host machine are same. 

Yes.  The first build of gcc has some limitations, and
isn't useful for building everything a normal gcc can build.
(In fact, one might consider building glibc a second time
just to get the little helper binaries it comes with
compiled right.)

> Second,
> Are these steps valid for cross compilation when build machine and host
> machine are same and target is different.
>
> 1.Build binutil and gcc in any order and for target and install them.
> 2.Configure kernel, get headers.
> 3.Cross compile glibc using above cross compiler and binutil.

That would be nice, but the circular dependencies between
gcc and glibc currently preclude it, I think.  Maybe
gcc-4.1 or gcc-5 will be refactored to make something
like that easier.  In the meantime, use crosstool to build
your toolchains if you can.
- Dan

--
Trying to get a job as a c++ developer?  See http://kegel.com/academy/getting-hired.html

------
Want more information?  See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/
Want to unsubscribe? Send a note to crossgcc-unsubscribe@sources.redhat.com