[Clfs-support] Building ARMv6 uClibc-ng cross-compiler

[Michele Bucca]

Il 21 nov 2016 2:41 PM, "Andrew Bradford" <andrew at bradfordembedded.com> ha
scritto:
>
> Hi Michele,
>
> On 11/18 23:38, Michele Bucca wrote:
> > Il 18 nov 2016 9:27 PM, "Andrew Bradford"
> > <andrew at bradfordembedded.com> ha scritto:
> > >
> > > Hi Michele,
> > >
> > > On 11/16 10:08, Michele Bucca wrote:
> > > > Hello, I'm trying to build a cross compiler for arm v6 machines
without
> > > > float on my computer. Debian 8
> > > >
> > > > the target I'm trying to use for the build is arm-linux-uclibc but
> > > > configure recognises it as arm-unknown-linux-uclibc and gcc does not
> > > > recognise as a valid target when I give the command "make"
> > >
> > > Can you share what the actual build error is?  And does this error
from
> > > make happen when you're compiling the first pass of GCC or at some
other
> > > time?
> >
> > the  error was gcc-all target not valid during the make process
>
> If you're able to provide the actual error output, that might be
> helpful.
>
> > >
> > > arm-unknown-linux-uclibc should be a valid triplet according to GCC,
as
> > > far as I can tell.
> >
> > I've used arm-unknown-linux-uclibcgnueabi
>
> I don't believe that's a valid triplet.  The "gnu" part in the last
> segment is to indicate glibc, normally.  The "eabi" is to indicate the
> newer ABI for ARM, which since you mention you're using Cortex-A53, is
> correct for your processor.
>
> Likely you want arm-unknown-linux-uclibceabi as your triplet.
>
arm-unknown-linux-uclibcgnueabi is used even by crosstool-ng

> > >
> > > What versions of binutils, GCC, and uClibc are you using?
> >
> > Gcc 6.2.0
> > Binutiils 2.27
> > uClibc-ng 1.0.17
> > MPC 1.0.3
> > GMP 6.1.1
> > MPFR 3.1.4
> > Linux 4.7.2
> >
> > >
> > > > There's no book on clfs.org that builds by hand a uclibc toolchain
and I
> > > > want to learn to build one to compile static software (qemu as a
console
> > > > command)to run on android. I've already succeeded building qemu
statically
> > > > with a glibc arm compiler but it does not work well as glibc suck
for
> > > > static compiling. Can you help me with building GCC? I'm building
the first
> > > > pass GCC
> > >
> > > Are you building for a no-mmu system?  If not, are you able to follow
> > > the current embedded book using musl libc and compile statically
linked
> > > executables?
> > >
> >
> > The CPU that will run the executables is a Qualcomm Snapdragon 400/410
> > Architecture ARM Cortex-A53 (revision r0p0)
> > I don't know anything else
> >
> > GCC is built using --with-arch=armv6 --with-float=soft
>
> Cortex-A53 is armv8-a, it likely will work fine executing armv6 binaries,
> but I find it odd that you're trying to do this.  Any reason why you're
> not using --with-arch=armv8-a or at least --with-arch=armv7?

Because I want to make sure that the executables will run even on the older
CPUs

>
> Are you trying to match a toolchain given to you by someone else?
>
> > > If you are able to build using musl, then at least it would narrow
down
> > > the problem to how you're using uClibc.
> >
> > On the page below it is shown that QEMU can't be build with musl. I
> > know that there are patches out there but I don't want to edit the
> > code of the tarball as I want to keep it as intact as possible.
> >
> > http://wiki.musl-libc.org/wiki/Pkgsrc_results
>
> In my experience, there are a decent number of packages in pkgsrc which
> don't build with musl where the build failure has nothing to do with
> musl specifically.  Unless you have specific knowledge of why the pkgsrc
> packages aren't building, it's not always good to put full faith in that
> test suite.
>
> Sabotage Linux [1] has a qemu package and uses musl, you may look at how
> they build it for some tips.
>
> [1]: https://github.com/sabotage-linux/sabotage
>
> > Like now I've installed uClibc, let's hope that anything will go well
> > (at least when building the toolchain)
> > I wanted to learn how to make this toolchain because all I can find
> > about arm uclibc toolchains is the buildroot package that may be
> > really neat for what I want to do but it does not let me to study how
> > the toolchain is made. To build this thing I'm using multiple sources:
> > the clfs-embedded book, the LFS book and sometimes even the CLFS-3.0
> > (sysvinit) book.
>
> Buildroot isn't hard to follow if you take a gander through their
> Makefiles, or just read through the output during a build.  It takes

i have to learn how makefiles work. I don't know not even the basics of
Makefiles

> some time to parse and understand, but their toolchain when using uClibc
> or musl is pretty simple and rather similar to how CLFS does things.
>
> You might also check out crosstool-ng [2] if you want a relatively easy
> to use toolchain creator system.
>
> [2]: http://crosstool-ng.org/
>

I'm studying even musl-cross to build the toolchain

https://bitbucket.org/GregorR/musl-cross/src/

> > I'll keep you Informed if you wish
> > If you have other suggestions or warnings that would be appreciated
>
> I'm happy to help if I can so long as you post your questions to the
> clfs-support list.
>
> Thanks,
> Andrew
>

Thank you Andrew,

-- Michele _______________________________________________
> Clfs-support mailing list
> Clfs-support at lists.clfs.org
> http://lists.clfs.org/listinfo.cgi/clfs-support-clfs.org
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