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

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

[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>
---
 mk/rte.module.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mk/rte.module.mk b/mk/rte.module.mk
index b3a630e..5d66d90 100644
--- a/mk/rte.module.mk
+++ b/mk/rte.module.mk
@@ -77,7 +77,7 @@ build: _postbuild
 # build module
 $(MODULE).ko: $(SRCS_LINKS)
 	@if [ ! -f $(notdir Makefile) ]; then ln -nfs $(SRCDIR)/Makefile . ; fi
-	@$(MAKE) -C $(RTE_KERNELDIR) M=$(CURDIR) O=$(RTE_KERNELDIR)
+	@$(MAKE) -C $(RTE_KERNELDIR) M=$(CURDIR) O=$(RTE_KERNELDIR) CROSS_COMPILE=$(CROSS)
 
 # install module in $(RTE_OUTPUT)/kmod
 $(RTE_OUTPUT)/kmod/$(MODULE).ko: $(MODULE).ko
-- 
1.8.5.1

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

[Thomas Monjalon]

Hi,

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.

Thanks
-- 
Thomas

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

[Aaro Koskinen]

Hi,

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.

A.

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

[Thomas Monjalon]

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