Re: [PATCH] ARC: Get rid of toolchain check

[gregkh@xxxxxxxxxxxxxxxxxxx]

On Wed, Oct 17, 2018 at 02:28:41PM +0000, Alexey Brodkin wrote:
> Hello,
> 
> > -----Original Message-----
> > From: Rob Herring [mailto:robh@xxxxxxxxxx]
> > Sent: Friday, September 14, 2018 12:04 AM
> > To: Alexey.Brodkin@xxxxxxxxxxxx
> > Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; Vineet.Gupta1@xxxxxxxxxxxx
> > Subject: Re: [PATCH] ARC: Get rid of toolchain check
> > 
> > On Thu, Sep 13, 2018 at 3:24 PM Alexey Brodkin
> > <Alexey.Brodkin@xxxxxxxxxxxx> wrote:
> > >
> > > This check is very naive: we simply test if GCC invoked without
> > > "-mcpu=XXX" has ARC700 define set. In that case we think that GCC
> > > was built with "--with-cpu=arc700" and has libgcc built for ARC700.
> > >
> > > Otherwise if ARC700 is not defined we think that everythng was built
> > > for ARCv2.
> > >
> > > But in reality our life is much more interesting.
> > >
> > > 1. Regardless of GCC configuration (i.e. what we pass in "--with-cpu"
> > >    it may generate code for any ARC core).
> > >
> > > 2. libgcc might be built with explicitly specified "--mcpu=YYY"
> > >
> > > That's exactly what happens in case of multilibbed toolchains:
> > >  - GCC is configured with default settings
> > >  - All the libs built for many different CPU flavors
> > >
> > > I.e. that check gets in the way of usage of multilibbed
> > > toolchains. And even non-multilibbed toolchains are affected.
> > > OpenEmbedded also builds GCC without "--with-cpu" because
> > > each and every target component later is compiled with explicitly
> > > set "-mcpu=ZZZ".
> > >
> > > Signed-off-by: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
> > > ---
> > >  arch/arc/Makefile | 14 --------------
> > >  1 file changed, 14 deletions(-)
> > 
> > +1 for this. Removing it also helps with my work to be able to build
> > all the .dts files with only a host compiler. That also needs the hunk
> > setting CROSS_COMPILE removed and not having a built-in dtb by
> > default, but this is a step in the right direction.
> > 
> > Acked-by: Rob Herring <robh@xxxxxxxxxx>
> 
> May we get this one back-ported to stable trees?
> 
> Upstream commit in Linus' tree is
> 615f64458ad8 ("ARC: build: Get rid of toolchain check").
> 
> This fixes kernel configuration for ARC in case of missing
> ARC cross-tools in current PATH.

Now queued up, thanks.

greg k-h