On Thu, Oct 29, 2015 at 10:46:49AM +0100, Ingo Molnar wrote:
> Would it be possible to add a gcc and glibc building portion as well? That would
> make it entirely self-hosting.
Yes, but:
- Those that intend to run the built binary on a target would presumably
already have a cross-compiler lying around which they use to build the
rest of userspace.
- Those that don't have a cross-compiler or need a newer one can already
very easily create one using other specialized tools such as
crosstool-ng (see below).
>
> Something like:
>
> make ARCH=arm BOOTSTRAP=1
>
> ... would magically fetch everything needed, and (given enough Internet bandwidth
> and a fast enough machine) build a whole cross-environment from scratch.
This is already possible using crosstool-ng. Getting an ARM GCC 5.2
cross-compiler is as simple as:
$ git clone git://crosstool-ng.org/crosstool-ng
$ cd crosstool-ng
$ ./bootstrap && ./configure --enable-local && make
$ ./ct-ng arm-unknown-linux-gnueabi
$ ./ct-ng build
$ export PATH=$PATH:~/x-tools/arm-unknown-linux-gnueabi/bin/
$ arm-unknown-linux-gnueabi-gcc --version
arm-unknown-linux-gnueabi-gcc (crosstool-NG crosstool-ng-1.20.0-361-g85f9814) 5.2.0
> Personally I'd even use this to bootstrap kernel cross-builds.
>
> It could also be used to cross-build to the host architecture as well: it would
> make it easier to test perf on the latest GCC and glibc versions. (Which the host
> distribution does not carry.)
This is also possible with crosstool-ng. You just need to build the
x86_64-unknown-linux-gnu config to get GCC 5.2 + glibc 2.22 toolchain
for an x86-64 host.
* Rabin Vincent <[email protected]> wrote:
> On Thu, Oct 29, 2015 at 10:46:49AM +0100, Ingo Molnar wrote:
> > Would it be possible to add a gcc and glibc building portion as well? That would
> > make it entirely self-hosting.
>
> Yes, but:
>
> - Those that intend to run the built binary on a target would presumably
> already have a cross-compiler lying around which they use to build the
> rest of userspace.
>
> - Those that don't have a cross-compiler or need a newer one can already
> very easily create one using other specialized tools such as
> crosstool-ng (see below).
>
> >
> > Something like:
> >
> > make ARCH=arm BOOTSTRAP=1
> >
> > ... would magically fetch everything needed, and (given enough Internet bandwidth
> > and a fast enough machine) build a whole cross-environment from scratch.
>
> This is already possible using crosstool-ng. Getting an ARM GCC 5.2
> cross-compiler is as simple as:
>
> $ git clone git://crosstool-ng.org/crosstool-ng
> $ cd crosstool-ng
> $ ./bootstrap && ./configure --enable-local && make
>
> $ ./ct-ng arm-unknown-linux-gnueabi
> $ ./ct-ng build
My point is, that's 5 non-trivial steps harder than just typing:
make ARCH=arm BOOTSTRAP=1
> This is also possible with crosstool-ng. You just need to build the
> x86_64-unknown-linux-gnu config to get GCC 5.2 + glibc 2.22 toolchain
> for an x86-64 host.
It's also possibly by directly cloning the repos of those tools and building them
- they are reasonably easy to build.
My point is that if we add automation, we might as well walk to whole mile.
Thanks,
Ingo