arm64: build with baremetal linker target instead of Linux when available
diff mbox

Message ID 20180713153033.20540-1-olof@lixom.net
State New
Headers show

Commit Message

Olof Johansson July 13, 2018, 3:30 p.m. UTC
Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
in particular. So, probe for whether it's available and use the previous
(linux) targets if it isn't.

Reported-by: Laura Abbott <labbott@redhat.com>
Cc: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: Olof Johansson <olof@lixom.net>
---
 arch/arm64/Makefile    | 9 +++++----
 scripts/Kbuild.include | 4 ++--
 2 files changed, 7 insertions(+), 6 deletions(-)

Comments

Laura Abbott July 13, 2018, 7:21 p.m. UTC | #1
On 07/13/2018 08:30 AM, Olof Johansson wrote:
> Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
> in particular. So, probe for whether it's available and use the previous
> (linux) targets if it isn't.
> 


For the Fedora toolchains:

Tested-by: Laura Abbott <labbott@redhat.com>

> Reported-by: Laura Abbott <labbott@redhat.com>
> Cc: Paul Kocialkowski <contact@paulk.fr>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> ---
>   arch/arm64/Makefile    | 9 +++++----
>   scripts/Kbuild.include | 4 ++--
>   2 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index e7101b19d590..efe61a2e4b5e 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -60,15 +60,16 @@ ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
>   KBUILD_CPPFLAGS	+= -mbig-endian
>   CHECKFLAGS	+= -D__AARCH64EB__
>   AS		+= -EB
> -# We must use the linux target here, since distributions don't tend to package
> -# the ELF linker scripts with binutils, and this results in a build failure.
> -LDFLAGS		+= -EB -maarch64linuxb
> +# Prefer the baremetal ELF build target, but not all toolchains include
> +# it so fall back to the standard linux version if needed.
> +LDFLAGS		+= -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
>   UTS_MACHINE	:= aarch64_be
>   else
>   KBUILD_CPPFLAGS	+= -mlittle-endian
>   CHECKFLAGS	+= -D__AARCH64EL__
>   AS		+= -EL
> -LDFLAGS		+= -EL -maarch64linux # See comment above
> +# Same as above, prefer ELF but fall back to linux target if needed.
> +LDFLAGS		+= -EL $(call ld-option, -maarch64elf, -maarch64linux)
>   UTS_MACHINE	:= aarch64
>   endif
>   
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index c8156d61678c..1e13f502b42f 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -163,8 +163,8 @@ cc-ldoption = $(call try-run,\
>   	$(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
>   
>   # ld-option
> -# Usage: LDFLAGS += $(call ld-option, -X)
> -ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
> +# Usage: LDFLAGS += $(call ld-option, -X, -Y)
> +ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2),$(3))
>   
>   # ar-option
>   # Usage: KBUILD_ARFLAGS := $(call ar-option,D)
> 

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Olof Johansson July 13, 2018, 7:58 p.m. UTC | #2
On Fri, Jul 13, 2018 at 12:21 PM, Laura Abbott <labbott@redhat.com> wrote:
> On 07/13/2018 08:30 AM, Olof Johansson wrote:
>>
>> Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
>> in particular. So, probe for whether it's available and use the previous
>> (linux) targets if it isn't.
>>
>
>
> For the Fedora toolchains:
>
> Tested-by: Laura Abbott <labbott@redhat.com>

Thanks!


-Olof
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Masahiro Yamada July 18, 2018, 11:08 p.m. UTC | #3
2018-07-14 0:30 GMT+09:00 Olof Johansson <olof@lixom.net>:
> Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
> in particular. So, probe for whether it's available and use the previous
> (linux) targets if it isn't.
>
> Reported-by: Laura Abbott <labbott@redhat.com>
> Cc: Paul Kocialkowski <contact@paulk.fr>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> ---
>  arch/arm64/Makefile    | 9 +++++----
>  scripts/Kbuild.include | 4 ++--
>  2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index e7101b19d590..efe61a2e4b5e 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -60,15 +60,16 @@ ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
>  KBUILD_CPPFLAGS        += -mbig-endian
>  CHECKFLAGS     += -D__AARCH64EB__
>  AS             += -EB
> -# We must use the linux target here, since distributions don't tend to package
> -# the ELF linker scripts with binutils, and this results in a build failure.
> -LDFLAGS                += -EB -maarch64linuxb
> +# Prefer the baremetal ELF build target, but not all toolchains include
> +# it so fall back to the standard linux version if needed.
> +LDFLAGS                += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
>  UTS_MACHINE    := aarch64_be
>  else
>  KBUILD_CPPFLAGS        += -mlittle-endian
>  CHECKFLAGS     += -D__AARCH64EL__
>  AS             += -EL
> -LDFLAGS                += -EL -maarch64linux # See comment above
> +# Same as above, prefer ELF but fall back to linux target if needed.
> +LDFLAGS                += -EL $(call ld-option, -maarch64elf, -maarch64linux)
>  UTS_MACHINE    := aarch64
>  endif
>
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index c8156d61678c..1e13f502b42f 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -163,8 +163,8 @@ cc-ldoption = $(call try-run,\
>         $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
>
>  # ld-option
> -# Usage: LDFLAGS += $(call ld-option, -X)
> -ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
> +# Usage: LDFLAGS += $(call ld-option, -X, -Y)
> +ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2),$(3))
>
>  # ar-option
>  # Usage: KBUILD_ARFLAGS := $(call ar-option,D)


I guess this patch will go through the arm64 tree.

I am fine with the change of scripts/Kbuild.include

Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Ard Biesheuvel July 19, 2018, 12:18 a.m. UTC | #4
On 14 July 2018 at 00:30, Olof Johansson <olof@lixom.net> wrote:
> Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
> in particular. So, probe for whether it's available and use the previous
> (linux) targets if it isn't.
>
> Reported-by: Laura Abbott <labbott@redhat.com>
> Cc: Paul Kocialkowski <contact@paulk.fr>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> ---
>  arch/arm64/Makefile    | 9 +++++----
>  scripts/Kbuild.include | 4 ++--
>  2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index e7101b19d590..efe61a2e4b5e 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -60,15 +60,16 @@ ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
>  KBUILD_CPPFLAGS        += -mbig-endian
>  CHECKFLAGS     += -D__AARCH64EB__
>  AS             += -EB
> -# We must use the linux target here, since distributions don't tend to package
> -# the ELF linker scripts with binutils, and this results in a build failure.
> -LDFLAGS                += -EB -maarch64linuxb
> +# Prefer the baremetal ELF build target, but not all toolchains include
> +# it so fall back to the standard linux version if needed.
> +LDFLAGS                += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
>  UTS_MACHINE    := aarch64_be
>  else
>  KBUILD_CPPFLAGS        += -mlittle-endian
>  CHECKFLAGS     += -D__AARCH64EL__
>  AS             += -EL
> -LDFLAGS                += -EL -maarch64linux # See comment above
> +# Same as above, prefer ELF but fall back to linux target if needed.
> +LDFLAGS                += -EL $(call ld-option, -maarch64elf, -maarch64linux)
>  UTS_MACHINE    := aarch64
>  endif
>

Did anyone check if just removing these options altogether would be an option?

The commit that introduced them does not even mention them, but only
mentions adding -mabi=lp64 to the cc/as flags:

commit 3d6a7b99e3fa29b92d6288487e057e0a596bd2b0
Author: Andrew Pinski <apinski@cavium.com>
Date:   Mon Sep 18 11:20:20 2017 +0100

    arm64: ensure the kernel is compiled for LP64

    The kernel needs to be compiled as a LP64 binary for ARM64, even when
    using a compiler that defaults to code-generation for the ILP32 ABI.
    Consequently, we need to explicitly pass '-mabi=lp64' (supported on
    gcc-4.9 and newer).



> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index c8156d61678c..1e13f502b42f 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -163,8 +163,8 @@ cc-ldoption = $(call try-run,\
>         $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
>
>  # ld-option
> -# Usage: LDFLAGS += $(call ld-option, -X)
> -ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
> +# Usage: LDFLAGS += $(call ld-option, -X, -Y)
> +ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2),$(3))
>
>  # ar-option
>  # Usage: KBUILD_ARFLAGS := $(call ar-option,D)
> --
> 2.11.0
>
>
> _______________________________________________
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> linux-arm-kernel@lists.infradead.org
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Patch
diff mbox

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index e7101b19d590..efe61a2e4b5e 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -60,15 +60,16 @@  ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
 KBUILD_CPPFLAGS	+= -mbig-endian
 CHECKFLAGS	+= -D__AARCH64EB__
 AS		+= -EB
-# We must use the linux target here, since distributions don't tend to package
-# the ELF linker scripts with binutils, and this results in a build failure.
-LDFLAGS		+= -EB -maarch64linuxb
+# Prefer the baremetal ELF build target, but not all toolchains include
+# it so fall back to the standard linux version if needed.
+LDFLAGS		+= -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
 UTS_MACHINE	:= aarch64_be
 else
 KBUILD_CPPFLAGS	+= -mlittle-endian
 CHECKFLAGS	+= -D__AARCH64EL__
 AS		+= -EL
-LDFLAGS		+= -EL -maarch64linux # See comment above
+# Same as above, prefer ELF but fall back to linux target if needed.
+LDFLAGS		+= -EL $(call ld-option, -maarch64elf, -maarch64linux)
 UTS_MACHINE	:= aarch64
 endif
 
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index c8156d61678c..1e13f502b42f 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -163,8 +163,8 @@  cc-ldoption = $(call try-run,\
 	$(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
 
 # ld-option
-# Usage: LDFLAGS += $(call ld-option, -X)
-ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
+# Usage: LDFLAGS += $(call ld-option, -X, -Y)
+ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2),$(3))
 
 # ar-option
 # Usage: KBUILD_ARFLAGS := $(call ar-option,D)