Re: [dpdk-dev] [PATCH] mk: pass CROSS_COMPILE when compiling kernel modules

[Thomas Monjalon <thomas.monjalon@6wind.com>]

Hi,

2014-03-07 15:32, Aaro Koskinen:
> On Tue, Feb 25, 2014 at 10:55:36PM +0100, Thomas Monjalon wrote:
> > 07/02/2014 18:44, Aaro Koskinen :
> > > Pass CROSS_COMPILE to the kernel build system when compiling kernel
> > > modules. Although we export CC etc. the top level kernel Makefile will
> > > override the environment. As a result it will end up using wrong tools
> > > if cross-compilation is desired but CROSS_COMPILE is not set.
> > > 
> > > Signed-off-by: Aaro Koskinen <aaro.koskinen@nsn.com>
> > 
> > Could you explain why it's needed ?
> > In a basic test, CC=$(CROSS)gcc in rte.vars.mk seems sufficient.
> 
> If you compile on 32-bit host to 64-bit target, the build fails with
> errors such as:
> 
> [...]include/linux/kernfs.h:331:1: note: expected 'const char *' but
> argument is of type 'const unsigned char *' kernfs_find_and_get(struct
> kernfs_node *kn, const char *name)
>  ^
> cc1: all warnings being treated as errors
> 
> Build with V=1 shows that following appears in the command line
> when compiling the kernel modules:
> 
> 	-isystem /usr/lib/gcc/i486-linux-gnu/4.8/include
> 
> With the patch this will be corrected to point to my target's sysroot:
> 
> 	-isystem /foo/bar/lib/gcc/x86_64-linux-gnu/4.8.2/include
> 
> And the build succeeds without any warnings.

Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

It's applied for version 1.6.0r2.

Thanks
-- 
Thomas