Build regressions/improvements in v4.9-rc1

[Thomas Petazzoni]

Hello,

On Thu, 27 Oct 2016 09:07:55 +0000, Alexey Brodkin wrote:

> > axs101 is using a 770 core, while the toolchain is built for the HS38
> > core. I'm somewhat surprised that a single ARC toolchain cannot produce
> > code for both 770 and HS38, but it seems to be the case.
> > 
> > So you need a separate toolchain for ARC770.  
> 
> Indeed axs101 uses ARC770 core which is ARCv1 AKA ARCompact ISA while
> axs103 sports the same base-board but CPU daughter-card contains ARC HS38 core
> which has ARCv2 ISA (binary incompatible with ARCompact).
> 
> Essentially both gcc and binutils will happily build for both architectures given
> proper options were passed on the command line. But Linux kernel gets linked with
> pre-built libgcc (it is a part of toolchain). And so it all boils down to a requirement
> to have multilibbed uClibc toolchain. Which we don't have.

Interesting. Why is libgcc linked with the kernel on ARC? I don't think
that's the case on other architectures: the kernel is freestanding and
provides everything that it needs without relying on the compiler
runtime.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com