GCC built for arc*-*-linux has "-mmedium-calls" implicitly enabled by default
thus we don't see any problems during Linux kernel compilation.
----------------------------->8------------------------
arc-linux-gcc -mcpu=arc700 -Q --help=target | grep calls
-mlong-calls [disabled]
-mmedium-calls [enabled]
----------------------------->8------------------------
But if we try to use so-called Elf32 toolchain with GCC configured for
arc*-*-elf* then we'd see the following failure:
----------------------------->8------------------------
init/do_mounts.o: In function 'init_rootfs':
do_mounts.c:(.init.text+0x108): relocation truncated to fit: R_ARC_S21W_PCREL
against symbol 'unregister_filesystem' defined in .text section in fs/filesystems.o
arc-elf32-ld: final link failed: Symbol needs debug section which does not exist
make: *** [vmlinux] Error 1
----------------------------->8------------------------
That happens because neither "-mmedium-calls" nor "-mlong-calls" are enabled in
Elf32 GCC:
----------------------------->8------------------------
arc-elf32-gcc -mcpu=arc700 -Q --help=target | grep calls
-mlong-calls [disabled]
-mmedium-calls [disabled]
----------------------------->8------------------------
Now to make it possible to use Elf32 toolchain for building Linux kernel
we're explicitly add "-mmedium-calls" to CFLAGS.
Signed-off-by: Alexey Brodkin <[email protected]>
Signed-off-by: Alexey Brodkin <[email protected]>
---
arch/arc/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index d37f49d6a27f..db9ce90c3cc0 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -16,7 +16,7 @@ endif
KBUILD_DEFCONFIG := nsim_700_defconfig
-cflags-y += -fno-common -pipe -fno-builtin -D__linux__
+cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7
cflags-$(CONFIG_ISA_ARCV2) += -mcpu=archs
--
2.16.2
On 05/16/2018 08:03 AM, Alexey Brodkin wrote:
> GCC built for arc*-*-linux has "-mmedium-calls" implicitly enabled by default
> thus we don't see any problems during Linux kernel compilation.
> ----------------------------->8------------------------
> arc-linux-gcc -mcpu=arc700 -Q --help=target | grep calls
> -mlong-calls [disabled]
> -mmedium-calls [enabled]
> ----------------------------->8------------------------
>
> But if we try to use so-called Elf32 toolchain with GCC configured for
> arc*-*-elf* then we'd see the following failure:
> ----------------------------->8------------------------
> init/do_mounts.o: In function 'init_rootfs':
> do_mounts.c:(.init.text+0x108): relocation truncated to fit: R_ARC_S21W_PCREL
> against symbol 'unregister_filesystem' defined in .text section in fs/filesystems.o
>
> arc-elf32-ld: final link failed: Symbol needs debug section which does not exist
> make: *** [vmlinux] Error 1
> ----------------------------->8------------------------
>
> That happens because neither "-mmedium-calls" nor "-mlong-calls" are enabled in
> Elf32 GCC:
> ----------------------------->8------------------------
> arc-elf32-gcc -mcpu=arc700 -Q --help=target | grep calls
> -mlong-calls [disabled]
> -mmedium-calls [disabled]
> ----------------------------->8------------------------
>
> Now to make it possible to use Elf32 toolchain for building Linux kernel
> we're explicitly add "-mmedium-calls" to CFLAGS.
>
> Signed-off-by: Alexey Brodkin <[email protected]>
> ---
> arch/arc/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
> index d37f49d6a27f..db9ce90c3cc0 100644
> --- a/arch/arc/Makefile
> +++ b/arch/arc/Makefile
> @@ -16,7 +16,7 @@ endif
>
> KBUILD_DEFCONFIG := nsim_700_defconfig
>
> -cflags-y += -fno-common -pipe -fno-builtin -D__linux__
> +cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
> cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7
> cflags-$(CONFIG_ISA_ARCV2) += -mcpu=archs
LGTM. Bbut while we are here, can you now remove -mmedium-calls for specific files
further down in the makefile.