Re: [PATCHv2 3/3] perf: add helper makefile for cross compiling libs

From: Rabin Vincent
Date: Fri Nov 06 2015 - 03:09:24 EST

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://
$ 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.
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