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Date:   Fri, 2 Mar 2018 19:43:06 -0600
From:   Richard Kuo <rkuo@codeaurora.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:QUALCOMM HEXAGON..." <linux-hexagon@vger.kernel.org>,
        Chen Liqin <liqin.linux@gmail.com>,
        Lennox Wu <lennox.wu@gmail.com>,
        Guan Xuetao <gxt@mprc.pku.edu.cn>,
        Guenter Roeck <linux@roeck-us.net>,
        Al Viro <viro@zeniv.linux.org.uk>,
        James Hogan <jhogan@kernel.org>,
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        Jonas Bonn <jonas@southpole.se>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Stafford Horne <shorne@gmail.com>,
        openrisc@lists.librecores.org, David Howells <dhowells@redhat.com>
Subject: Re: Removing architectures without upstream gcc support
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On Wed, Feb 28, 2018 at 09:37:09AM +0100, Arnd Bergmann wrote:
> On Wed, Feb 28, 2018 at 3:06 AM, Richard Kuo <rkuo@codeaurora.org> wrote:
> > On Thu, Feb 22, 2018 at 11:43:10PM +0100, Arnd Bergmann wrote:
> >> - How do I build an llvm based toolchain for Hexagon? Do I need patches
> >>   on top of the llvm-6 release branch? Where can I find the corresponding
> >>   binutils-2.30 sources?
> >
> > Just to follow up on this, the closest thing right now to compile the kernel
> > for Hexagon is the toolchain included with the Hexagon SDK.  However, the
> > linker will fail because of something in the kernel build process that
> > I think produces empty sections, which that linker can't handle.  A newer
> > linker can handle it, but that's not scheduled to be released until much later
> > this year.
> >
> > That's actually the closest option currently.  I tried the upstream source
> > but it seems to lack some specific patches to support kernel compilation,
> > so I will need to chase those down.
> 
> Thanks for trying it out. Can you point me to the sources? I tried downloading
> a Hexagon SDK when I first looked at it, but only got a huge chunk of binary
> java files and gave up before finding the llvm patches.


I don't think the SDK patches are available externally.

The good news is I think we're now one patch away from the upstream LLVM
compiling a functional kernel for Hexagon (a few fixes to LLVM/clang have
been committed already).  It technically compiles but produces an abort (from
a null deref) which the linker doesn't like.

The linker itself unfortunately is going to be a different matter.


Thanks,
Richard Kuo


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