Re: [ptxdist] Go in ptxdist

[Michael Olbrich <m.olbrich@pengutronix.de>]

Hi,

On Wed, Oct 05, 2016 at 05:55:10PM +0200, Clemens Gruber wrote:
> On Wed, Oct 05, 2016 at 03:13:27PM +0200, Michael Olbrich wrote:
> > I'd prefer it if we cleaned up the arm architecture stuff in
> > architecture.in to make this explicit.
> 
> Do you mean adding config options for V5 and V7?
> And then deducing the correct GOARCH and GOARM from the ptxconfig
> settings instead of the used toolchain's ABI?

We should probably have options for v5/v6/v7 and for armel vs. armhf. And
checks, that the toolchain does the right thing. And then use these options
to configure Go correctly.

Side note: the toolchain check is non-trivial because there are gcc
versions that produce armhf code but do not define any macros that we could
use to identify this. I need to think about how to check this correctly.

This would be also interesting for other use-cases: I've worked with binary
software (OpenGL drives etc.) that couldn't compile. In that case, this
would be great to make sure things are consistent.
Mixing armel and armhf library does _not_ fail when starting the
application, but breaks later because the function argument are not
interpreted correctly...

> > > Go supports >=ARMv6 builds with hardfloat only, so I'd fall back to
> > > building ARMv5 binaries for ARMv6/7 softfloat configurations.
> > 
> > Are you sure this means it cannot create armv6/7 softfloat?
> 
> They write: "ARM on Linux. You must run an EABI kernel. These are
> generally known as armel for softfloat (compatible with ARMv5) or armhf
> for hardware floating point (ARMv6 and above)."
> 
> If you set GOARM to 6 or 7 it always creates hardfloat code. So I think,
> setting it to anything else than 5 would lead to a crash on all
> architectures without a VFP unit?

This description is a bit vague. In general, whether armel or armhf is used
does not depend on the ARM architecture, so armel on ARMv7 (and using
floating point instructions!) is perfectly valid.
We need to investigate if armhf is just the default for ARMv6/7 or if that
can be configured.

Michael

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
ptxdist mailing list
ptxdist@pengutronix.de