Want to run L4Re on Raspberry PI.

[Matthias Lange]

On [29-05-2019 14:35], Paul Boddie wrote:
> On Wednesday 29. May 2019 08.39.11 Matthias Lange wrote:
> > 
> > On [28-05-2019 21:21], Lei Zhou wrote:
> > > Thanks Paul for your prompt response.  I will give it try and see how it
> > > goes.    Regards,   Lei
> > I just want to add two things to Paul's very good description.
> > 
> > First, have you checked our build instructions and how tos on our github [1]
> > ?
> 
> Maybe there should be some updates to l4re.org to communicate any new advice.
> 
> > And second, which Raspberry Pi model are you targeting? Newer (> gcc 4.7)
> > cross-toolchains seem to have dropped support for ARMv6k. While you still
> > can compile L4Re/Fiasco for that architecture the binaries will not run
> > later.
> 
> One thing I did forget to mention was the cross-toolchains, which was 
> regrettable. I believe that the Debian toolchains in Debian 9 (Stretch), 10 
> (Buster) or unstable (Sid) should be good enough, but as is noted above, the 
> architecture variant of earlier Raspberry Pi models (and the Pi Zero) is not 
> supported in Debian any more (which is why Raspbian exists).
> 
> I suppose that L4Re could be compiled natively within Raspbian if that is 
> already deployed. I don't remember if there are any complications for ARM 
> about code output, but looking at the src/l4/mk/arch/Makeconf.arm, it seems 
> that a fairly standard arm-linux-gnueabihf toolchain is indicated. (I suppose 
> I could be thinking about certain "bare metal" configurations requiring 
> differently-configured compilers.)

The issue we have with "standard" cross toolchains is the libgcc they are
shipping. It is compiled for ARMv7 and contains instructions that are
unknown / illegal on ARMv6k. The mean thing is, that our build system tells
GCC via "-march=armv6zk" what code to generate but then links the wrong
libgcc.

Matthias.

> 
> Otherwise, I had some success with Buildroot in generating toolchains, these 
> being needed for my soft-float MIPS configuration.
> 
> Paul
> 
> > [1] https://github.com/kernkonzept/manifest/wiki

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Matthias Lange, matthias.lange at kernkonzept.com, +49-351-41 888 614

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