Patchwork Clarify MIPS ABIs support

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Submitter Thomas Petazzoni
Date July 24, 2012, 8:47 p.m.
Message ID <1343162828-13060-1-git-send-email-thomas.petazzoni@free-electrons.com>
Download mbox | patch
Permalink /patch/173052/
State Superseded
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Comments

Thomas Petazzoni - July 24, 2012, 8:47 p.m.
Practically speaking, MIPS has three useful ABIs:

 * o32 is for 32-bits CPUs, or 64-bit CPUs running only a 32-bit subset
   of the instruction set.
 * n32 is for 64-bits CPUs only. It has 32-bits pointers and long
   integers.
 * n64 is for 64-bits CPUs only. It has 64-bits pointers and long
   integers.

See http://www.linux-mips.org/wiki/MIPS_ABI_History and
http://www.linux-mips.org/wiki/WhatsWrongWithO32N32N64 for more
details.

So, this commit reworks the Buildroot MIPS support by:

 * Renaming the n32 ABI option to BR2_MIPS_NABI32, for consistency
   with BR2_MIPS_OABI32.

 * Renaming the n64 ABI option to BR2_MIPS_NABI64, for consistency
   with BR2_MIPS_OABI32.

 * Make the n32 and n64 ABI selections select the BR2_ARCH_IS_64,
   since those ABIs are valid on 64-bits CPUs only.

 * Removing the o64 ABI, which is practicaly never used.

 * Removing the "none" ABI, which really doesn't make sense.

 * Introduce the mips64 and mips64el architecture names when a 64-bits
   MIPS ABI is choosen. This will fix build issue like
   http://autobuild.buildroot.org/results/9b8c5ea86c953a89e85e7b67e9221de41773f652/build-end.log
   where gmp was confused by the fact of having a 32 bits architecture
   (detected by the mips- architecture part of the tuple) but 64 bits
   integer size when compiling.

 * Adjust the uclibc.mk logic to support the new mips64/mips64el
   architecture names, and take into account the renaming of the ABI
   options.

This has been build tested by generating Buildroot toolchains and
compiling a few packages for MIPS o32, MIPS n32 and MIPS n64.

This work is originally based on prior work done by Gustavo Zacarias.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 package/Makefile.in        |    2 +-
 target/Config.in.arch      |   28 +++++++++++-----------------
 toolchain/uClibc/uclibc.mk |    9 ++++++---
 3 files changed, 18 insertions(+), 21 deletions(-)
Thomas Petazzoni - July 25, 2012, 4:29 p.m.
Hello Gustavo,

If you could have a look at the below patch, and provide your comments
or Acked-by, it would be great.

Thanks a lot!

Thomas

Le Tue, 24 Jul 2012 22:47:08 +0200,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a écrit :

> Practically speaking, MIPS has three useful ABIs:
> 
>  * o32 is for 32-bits CPUs, or 64-bit CPUs running only a 32-bit subset
>    of the instruction set.
>  * n32 is for 64-bits CPUs only. It has 32-bits pointers and long
>    integers.
>  * n64 is for 64-bits CPUs only. It has 64-bits pointers and long
>    integers.
> 
> See http://www.linux-mips.org/wiki/MIPS_ABI_History and
> http://www.linux-mips.org/wiki/WhatsWrongWithO32N32N64 for more
> details.
> 
> So, this commit reworks the Buildroot MIPS support by:
> 
>  * Renaming the n32 ABI option to BR2_MIPS_NABI32, for consistency
>    with BR2_MIPS_OABI32.
> 
>  * Renaming the n64 ABI option to BR2_MIPS_NABI64, for consistency
>    with BR2_MIPS_OABI32.
> 
>  * Make the n32 and n64 ABI selections select the BR2_ARCH_IS_64,
>    since those ABIs are valid on 64-bits CPUs only.
> 
>  * Removing the o64 ABI, which is practicaly never used.
> 
>  * Removing the "none" ABI, which really doesn't make sense.
> 
>  * Introduce the mips64 and mips64el architecture names when a 64-bits
>    MIPS ABI is choosen. This will fix build issue like
>    http://autobuild.buildroot.org/results/9b8c5ea86c953a89e85e7b67e9221de41773f652/build-end.log
>    where gmp was confused by the fact of having a 32 bits architecture
>    (detected by the mips- architecture part of the tuple) but 64 bits
>    integer size when compiling.
> 
>  * Adjust the uclibc.mk logic to support the new mips64/mips64el
>    architecture names, and take into account the renaming of the ABI
>    options.
> 
> This has been build tested by generating Buildroot toolchains and
> compiling a few packages for MIPS o32, MIPS n32 and MIPS n64.
> 
> This work is originally based on prior work done by Gustavo Zacarias.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  package/Makefile.in        |    2 +-
>  target/Config.in.arch      |   28 +++++++++++-----------------
>  toolchain/uClibc/uclibc.mk |    9 ++++++---
>  3 files changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 6fad224..21b8634 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -87,7 +87,7 @@ endif
>  
>  TARGET_CFLAGS=$(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING)
>  
> -ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_ABI64)),yy)
> +ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_NABI64)),yy)
>  TARGET_CFLAGS+=-fno-pic -mno-abicalls
>  endif
>  
> diff --git a/target/Config.in.arch b/target/Config.in.arch
> index e7aec56..0ef59ef 100644
> --- a/target/Config.in.arch
> +++ b/target/Config.in.arch
> @@ -271,26 +271,20 @@ choice
>  	prompt "Target ABI"
>  	depends on BR2_mips || BR2_mipsel
>  	default BR2_MIPS_OABI32 if BR_mips_32 || BR_mips_32r2
> -	default BR2_MIPS_ABI32 if BR_mips_64 || BR_mips_64r2
> +	default BR2_MIPS_NABI32 if BR_mips_64 || BR_mips_64r2
>  	help
>  	  Application Binary Interface to use
>  
>  config BR2_MIPS_OABI32
>  	bool "o32"
> -config BR2_MIPS_ABI32
> +config BR2_MIPS_NABI32
>  	bool "n32"
> +	select BR2_ARCH_IS_64
>  	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI64
> +config BR2_MIPS_NABI64
>  	bool "n64"
> +	select BR2_ARCH_IS_64
>  	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_OABI64
> -	bool "o64"
> -	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI_none
> -	bool "unspecified"
> -	depends on BR2_mips_16
> -	help
> -	  Unspecified ABI leaves ABI selection blank.
>  endchoice
>  
>  choice
> @@ -688,8 +682,10 @@ config BR2_ARCH
>  	default "i686"		if BR2_x86_athlon_4
>  	default "m68k"		if BR2_m68k
>  	default "microblaze"	if BR2_microblaze
> -	default "mips"		if BR2_mips
> -	default "mipsel"	if BR2_mipsel
> +	default "mips"		if BR2_mips && !BR2_ARCH_IS_64
> +	default "mipsel"	if BR2_mipsel && !BR2_ARCH_IS_64
> +	default "mips64"	if BR2_mips && BR2_ARCH_IS_64
> +	default "mips64el"	if BR2_mipsel && BR2_ARCH_IS_64
>  	default "powerpc"	if BR2_powerpc
>  	default "sh2"		if BR2_sh2
>  	default "sh2a"		if BR2_sh2a
> @@ -904,10 +900,8 @@ config BR2_GCC_TARGET_ABI
>  	default aapcs		if BR2_arm_dunno
>  	default aapcs-linux	if BR2_ARM_EABI
>  	default 32		if BR2_MIPS_OABI32
> -	default n32		if BR2_MIPS_ABI32
> -	default eabi		if BR2_MIPS_EABI
> -	default o64		if BR2_MIPS_OABI64
> -	default 64		if BR2_MIPS_ABI64
> +	default n32		if BR2_MIPS_NABI32
> +	default 64		if BR2_MIPS_NABI64
>  	default mmixware	if BR2_mmix && BR2_MMIX_ABI_native
>  	default gnu		if BR2_mmix && !BR2_MMIX_ABI_native
>  	default altivec		if BR2_powerpc && BR2_PPC_ABI_altivec
> diff --git a/toolchain/uClibc/uclibc.mk b/toolchain/uClibc/uclibc.mk
> index 9d0b6db..aff0a60 100644
> --- a/toolchain/uClibc/uclibc.mk
> +++ b/toolchain/uClibc/uclibc.mk
> @@ -38,6 +38,7 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  		-e 's/sh[234].*/sh/' \
>  		-e 's/mips.*/mips/' \
>  		-e 's/mipsel.*/mips/' \
> +		-e 's/mips64el.*/mips/' \
>  		-e 's/cris.*/cris/' \
>  		-e 's/xtensa.*/xtensa/' \
>  ")
> @@ -45,6 +46,8 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  UCLIBC_TARGET_ENDIAN:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  		-e 's/armeb/BIG/' \
>  		-e 's/arm/LITTLE/' \
> +		-e 's/mips64el/LITTLE/' \
> +		-e 's/mips64/BIG/' \
>  		-e 's/mipsel/LITTLE/' \
>  		-e 's/mips/BIG/' \
>  		-e 's/sh.*eb/BIG/' \
> @@ -155,13 +158,13 @@ ifeq ($(UCLIBC_TARGET_ARCH),mips)
>  	 /bin/echo "# CONFIG_MIPS_ISA_MIPS32R2 is not set"; \
>  	 /bin/echo "# CONFIG_MIPS_ISA_MIPS64 is not set"; \
>  	) >> $(UCLIBC_DIR)/.oldconfig
> -ifeq ($(BR2_MIPS_OABI),y)
> +ifeq ($(BR2_MIPS_OABI32),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_O32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
> -ifeq ($(BR2_MIPS_ABI32),y)
> +ifeq ($(BR2_MIPS_NABI32),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_N32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
> -ifeq ($(BR2_MIPS_ABI64),y)
> +ifeq ($(BR2_MIPS_NABI64),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_N64_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
>  ifeq ($(BR2_mips_1),y)
Arnout Vandecappelle - July 25, 2012, 5:32 p.m.
On 07/24/12 22:47, Thomas Petazzoni wrote:
> So, this commit reworks the Buildroot MIPS support by:
>
>   * Renaming the n32 ABI option to BR2_MIPS_NABI32, for consistency
>     with BR2_MIPS_OABI32.
>
>   * Renaming the n64 ABI option to BR2_MIPS_NABI64, for consistency
>     with BR2_MIPS_OABI32.
>
>   * Make the n32 and n64 ABI selections select the BR2_ARCH_IS_64,
>     since those ABIs are valid on 64-bits CPUs only.

  As far as I understand, the situation is a bit similar to PCs, where
i386 and x86_64 are in fact quite different even at instruction set
level.  So wouldn't it make more sense to distinguish mips and mips64
at the 'Target Architecture' level?  Then mips would always select
o32, and the ABI choice would only exist for mips64.  And there
would be a 1-to-1 mapping between BR2_ARCH and the user choice,
which makes more sense to me.

  It would require a bit of research to find out which sub-architectures
are 64-bit, of course.


>   * Removing the o64 ABI, which is practicaly never used.
>
>   * Removing the "none" ABI, which really doesn't make sense.
>
>   * Introduce the mips64 and mips64el architecture names when a 64-bits
>     MIPS ABI is choosen. This will fix build issue like
>     http://autobuild.buildroot.org/results/9b8c5ea86c953a89e85e7b67e9221de41773f652/build-end.log
>     where gmp was confused by the fact of having a 32 bits architecture
>     (detected by the mips- architecture part of the tuple) but 64 bits
>     integer size when compiling.
>
>   * Adjust the uclibc.mk logic to support the new mips64/mips64el
>     architecture names, and take into account the renaming of the ABI
>     options.
>
> This has been build tested by generating Buildroot toolchains and
> compiling a few packages for MIPS o32, MIPS n32 and MIPS n64.
>
> This work is originally based on prior work done by Gustavo Zacarias.
>
> Signed-off-by: Thomas Petazzoni<thomas.petazzoni@free-electrons.com>
> ---
>   package/Makefile.in        |    2 +-
>   target/Config.in.arch      |   28 +++++++++++-----------------
>   toolchain/uClibc/uclibc.mk |    9 ++++++---
>   3 files changed, 18 insertions(+), 21 deletions(-)
>
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 6fad224..21b8634 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -87,7 +87,7 @@ endif
>
>   TARGET_CFLAGS=$(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING)
>
> -ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_ABI64)),yy)
> +ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_NABI64)),yy)

  Any reason why this isn't just

ifeq ($(BR2_MIPS_NABI64),y)

>   TARGET_CFLAGS+=-fno-pic -mno-abicalls
>   endif
>
> diff --git a/target/Config.in.arch b/target/Config.in.arch
> index e7aec56..0ef59ef 100644
> --- a/target/Config.in.arch
> +++ b/target/Config.in.arch
> @@ -271,26 +271,20 @@ choice
>   	prompt "Target ABI"
>   	depends on BR2_mips || BR2_mipsel
>   	default BR2_MIPS_OABI32 if BR_mips_32 || BR_mips_32r2
> -	default BR2_MIPS_ABI32 if BR_mips_64 || BR_mips_64r2
> +	default BR2_MIPS_NABI32 if BR_mips_64 || BR_mips_64r2
>   	help
>   	  Application Binary Interface to use
>
>   config BR2_MIPS_OABI32
>   	bool "o32"
> -config BR2_MIPS_ABI32
> +config BR2_MIPS_NABI32
>   	bool "n32"
> +	select BR2_ARCH_IS_64
>   	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI64
> +config BR2_MIPS_NABI64
>   	bool "n64"
> +	select BR2_ARCH_IS_64
>   	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_OABI64
> -	bool "o64"
> -	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI_none
> -	bool "unspecified"
> -	depends on BR2_mips_16
> -	help
> -	  Unspecified ABI leaves ABI selection blank.
>   endchoice
>
>   choice
> @@ -688,8 +682,10 @@ config BR2_ARCH
>   	default "i686"		if BR2_x86_athlon_4
>   	default "m68k"		if BR2_m68k
>   	default "microblaze"	if BR2_microblaze
> -	default "mips"		if BR2_mips
> -	default "mipsel"	if BR2_mipsel
> +	default "mips"		if BR2_mips&&  !BR2_ARCH_IS_64
> +	default "mipsel"	if BR2_mipsel&&  !BR2_ARCH_IS_64
> +	default "mips64"	if BR2_mips&&  BR2_ARCH_IS_64
> +	default "mips64el"	if BR2_mipsel&&  BR2_ARCH_IS_64
>   	default "powerpc"	if BR2_powerpc
>   	default "sh2"		if BR2_sh2
>   	default "sh2a"		if BR2_sh2a
> @@ -904,10 +900,8 @@ config BR2_GCC_TARGET_ABI
>   	default aapcs		if BR2_arm_dunno
>   	default aapcs-linux	if BR2_ARM_EABI
>   	default 32		if BR2_MIPS_OABI32
> -	default n32		if BR2_MIPS_ABI32
> -	default eabi		if BR2_MIPS_EABI
> -	default o64		if BR2_MIPS_OABI64
> -	default 64		if BR2_MIPS_ABI64
> +	default n32		if BR2_MIPS_NABI32
> +	default 64		if BR2_MIPS_NABI64
>   	default mmixware	if BR2_mmix &&  BR2_MMIX_ABI_native
>   	default gnu		if BR2_mmix &&  !BR2_MMIX_ABI_native

  Unrelated, but what is this BR2_mmix?

>   	default altivec		if BR2_powerpc&&  BR2_PPC_ABI_altivec
> diff --git a/toolchain/uClibc/uclibc.mk b/toolchain/uClibc/uclibc.mk
> index 9d0b6db..aff0a60 100644
> --- a/toolchain/uClibc/uclibc.mk
> +++ b/toolchain/uClibc/uclibc.mk
> @@ -38,6 +38,7 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>   		-e 's/sh[234].*/sh/' \
>   		-e 's/mips.*/mips/' \
>   		-e 's/mipsel.*/mips/' \
> +		-e 's/mips64el.*/mips/' \

  This one is already covered by the mips.* expression.  Actually,
so is the mipsel.* one.


  Regards,
  Arnout


>   		-e 's/cris.*/cris/' \
>   		-e 's/xtensa.*/xtensa/' \
>   ")
> @@ -45,6 +46,8 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>   UCLIBC_TARGET_ENDIAN:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>   		-e 's/armeb/BIG/' \
>   		-e 's/arm/LITTLE/' \
> +		-e 's/mips64el/LITTLE/' \
> +		-e 's/mips64/BIG/' \
>   		-e 's/mipsel/LITTLE/' \
>   		-e 's/mips/BIG/' \
>   		-e 's/sh.*eb/BIG/' \
> @@ -155,13 +158,13 @@ ifeq ($(UCLIBC_TARGET_ARCH),mips)
>   	 /bin/echo "# CONFIG_MIPS_ISA_MIPS32R2 is not set"; \
>   	 /bin/echo "# CONFIG_MIPS_ISA_MIPS64 is not set"; \
>   	)>>  $(UCLIBC_DIR)/.oldconfig
> -ifeq ($(BR2_MIPS_OABI),y)
> +ifeq ($(BR2_MIPS_OABI32),y)
>   	$(SED) 's/.*\(CONFIG_MIPS_O32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>   endif
> -ifeq ($(BR2_MIPS_ABI32),y)
> +ifeq ($(BR2_MIPS_NABI32),y)
>   	$(SED) 's/.*\(CONFIG_MIPS_N32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>   endif
> -ifeq ($(BR2_MIPS_ABI64),y)
> +ifeq ($(BR2_MIPS_NABI64),y)
>   	$(SED) 's/.*\(CONFIG_MIPS_N64_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>   endif
>   ifeq ($(BR2_mips_1),y)
Thomas Petazzoni - July 25, 2012, 6:25 p.m.
Le Wed, 25 Jul 2012 19:32:26 +0200,
Arnout Vandecappelle <arnout@mind.be> a écrit :

>   As far as I understand, the situation is a bit similar to PCs, where
> i386 and x86_64 are in fact quite different even at instruction set
> level.  So wouldn't it make more sense to distinguish mips and mips64
> at the 'Target Architecture' level?  Then mips would always select
> o32, and the ABI choice would only exist for mips64.  And there
> would be a 1-to-1 mapping between BR2_ARCH and the user choice,
> which makes more sense to me.

Makes sense. Gustavo, what do you think?

>   It would require a bit of research to find out which sub-architectures
> are 64-bit, of course.

Right, but it should be doable. The linux-mips.org Wiki has some info,
and I know someone who has quite a bit of experience with MIPS stuff,
so I could ask.

> > -ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_ABI64)),yy)
> > +ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_NABI64)),yy)
> 
>   Any reason why this isn't just
> 
> ifeq ($(BR2_MIPS_NABI64),y)

No, it could be this way. The bigger question is:

> >   TARGET_CFLAGS+=-fno-pic -mno-abicalls

Why are those special CFLAGS needed from the beginning?

> >   	default mmixware	if BR2_mmix &&  BR2_MMIX_ABI_native
> >   	default gnu		if BR2_mmix &&  !BR2_MMIX_ABI_native
> 
>   Unrelated, but what is this BR2_mmix?

It seems like the BR2_mmix option never existed in Buildroot. But from
a quick Google search, MMIX appears to be the fake architecture created
by Donald Knuth, which is the descendant of the MIX architecture he
created to illustrate the Art of Computer Programming. See
http://www-cs-faculty.stanford.edu/~uno/mmix.html. I don't think we
really want to support this architecture.

>   This one is already covered by the mips.* expression.  Actually,
> so is the mipsel.* one.

Right.

Thomas
Thomas Petazzoni - July 25, 2012, 6:31 p.m.
Le Wed, 25 Jul 2012 20:25:03 +0200,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a écrit :

> Le Wed, 25 Jul 2012 19:32:26 +0200,
> Arnout Vandecappelle <arnout@mind.be> a écrit :
> 
> >   As far as I understand, the situation is a bit similar to PCs, where
> > i386 and x86_64 are in fact quite different even at instruction set
> > level.  So wouldn't it make more sense to distinguish mips and mips64
> > at the 'Target Architecture' level?  Then mips would always select
> > o32, and the ABI choice would only exist for mips64.  And there
> > would be a 1-to-1 mapping between BR2_ARCH and the user choice,
> > which makes more sense to me.
> 
> Makes sense. Gustavo, what do you think?
> 
> >   It would require a bit of research to find out which sub-architectures
> > are 64-bit, of course.
> 
> Right, but it should be doable. The linux-mips.org Wiki has some info,
> and I know someone who has quite a bit of experience with MIPS stuff,
> so I could ask.

Thinking more about this, the way we do things for i386 vs. x86_64 is
not optimal: there are two complete distinct sets of entries for the
processor types. One for i386, one for x86_64. However, there should
normally be a big overlap between the two, since all x86_64 processors
support the i386 architecture. So maybe we should have a single list,
with certain processor not being visible in the i386. This would ensure
consistency between the list of processors available on i386 and x86_64.

Thoughts?

Thomas
Gustavo Zacarias - July 25, 2012, 8:25 p.m.
On 07/25/12 15:25, Thomas Petazzoni wrote:

> Le Wed, 25 Jul 2012 19:32:26 +0200,
> Arnout Vandecappelle <arnout@mind.be> a écrit :
> 
>>   As far as I understand, the situation is a bit similar to PCs, where
>> i386 and x86_64 are in fact quite different even at instruction set
>> level.  So wouldn't it make more sense to distinguish mips and mips64
>> at the 'Target Architecture' level?  Then mips would always select
>> o32, and the ABI choice would only exist for mips64.  And there
>> would be a 1-to-1 mapping between BR2_ARCH and the user choice,
>> which makes more sense to me.
> 
> Makes sense. Gustavo, what do you think?

Yes, it's the best option since we'll have the same dilemma sooner or
latter with powerpc(64) for example.

> No, it could be this way. The bigger question is:
> 
>>>   TARGET_CFLAGS+=-fno-pic -mno-abicalls
> 
> Why are those special CFLAGS needed from the beginning?

From what i could unearth it basically breaks dynamic linking though it
makes for smaller binaries.
I've tried removing it in my tests to get uClibc dynamic linking working
but something else is wrong, seemingly in the uClibc side.
For starters the loader is wrong, ld-linux in the target vs. ld64-linux
wanted by ELF files. And it seems there's something funky in the uClibc
Makefile about that (wants mips64 arch to build it, but they're using
unified ARCH as the kernel, so...)
Regards.
Thomas Petazzoni - July 25, 2012, 8:38 p.m.
Le Wed, 25 Jul 2012 17:25:11 -0300,
Gustavo Zacarias <gustavo@zacarias.com.ar> a écrit :

> > Makes sense. Gustavo, what do you think?
> 
> Yes, it's the best option since we'll have the same dilemma sooner or
> latter with powerpc(64) for example.

Ok.

> > No, it could be this way. The bigger question is:
> > 
> >>>   TARGET_CFLAGS+=-fno-pic -mno-abicalls
> > 
> > Why are those special CFLAGS needed from the beginning?
> 
> From what i could unearth it basically breaks dynamic linking though it
> makes for smaller binaries.
> I've tried removing it in my tests to get uClibc dynamic linking working
> but something else is wrong, seemingly in the uClibc side.
> For starters the loader is wrong, ld-linux in the target vs. ld64-linux
> wanted by ELF files. And it seems there's something funky in the uClibc
> Makefile about that (wants mips64 arch to build it, but they're using
> unified ARCH as the kernel, so...)

Do you have a working mips64 kernel under Qemu? I vaguely remember that
you said that it was working with statically linked binary, but not
dynamically linked ones. Is this correct?

If you have a working mips64 kernel under Qemu, I'm interested by the
kernel config and Qemu config.

Thanks,

Thomas

Patch

diff --git a/package/Makefile.in b/package/Makefile.in
index 6fad224..21b8634 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -87,7 +87,7 @@  endif
 
 TARGET_CFLAGS=$(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING)
 
-ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_ABI64)),yy)
+ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_NABI64)),yy)
 TARGET_CFLAGS+=-fno-pic -mno-abicalls
 endif
 
diff --git a/target/Config.in.arch b/target/Config.in.arch
index e7aec56..0ef59ef 100644
--- a/target/Config.in.arch
+++ b/target/Config.in.arch
@@ -271,26 +271,20 @@  choice
 	prompt "Target ABI"
 	depends on BR2_mips || BR2_mipsel
 	default BR2_MIPS_OABI32 if BR_mips_32 || BR_mips_32r2
-	default BR2_MIPS_ABI32 if BR_mips_64 || BR_mips_64r2
+	default BR2_MIPS_NABI32 if BR_mips_64 || BR_mips_64r2
 	help
 	  Application Binary Interface to use
 
 config BR2_MIPS_OABI32
 	bool "o32"
-config BR2_MIPS_ABI32
+config BR2_MIPS_NABI32
 	bool "n32"
+	select BR2_ARCH_IS_64
 	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
-config BR2_MIPS_ABI64
+config BR2_MIPS_NABI64
 	bool "n64"
+	select BR2_ARCH_IS_64
 	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
-config BR2_MIPS_OABI64
-	bool "o64"
-	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
-config BR2_MIPS_ABI_none
-	bool "unspecified"
-	depends on BR2_mips_16
-	help
-	  Unspecified ABI leaves ABI selection blank.
 endchoice
 
 choice
@@ -688,8 +682,10 @@  config BR2_ARCH
 	default "i686"		if BR2_x86_athlon_4
 	default "m68k"		if BR2_m68k
 	default "microblaze"	if BR2_microblaze
-	default "mips"		if BR2_mips
-	default "mipsel"	if BR2_mipsel
+	default "mips"		if BR2_mips && !BR2_ARCH_IS_64
+	default "mipsel"	if BR2_mipsel && !BR2_ARCH_IS_64
+	default "mips64"	if BR2_mips && BR2_ARCH_IS_64
+	default "mips64el"	if BR2_mipsel && BR2_ARCH_IS_64
 	default "powerpc"	if BR2_powerpc
 	default "sh2"		if BR2_sh2
 	default "sh2a"		if BR2_sh2a
@@ -904,10 +900,8 @@  config BR2_GCC_TARGET_ABI
 	default aapcs		if BR2_arm_dunno
 	default aapcs-linux	if BR2_ARM_EABI
 	default 32		if BR2_MIPS_OABI32
-	default n32		if BR2_MIPS_ABI32
-	default eabi		if BR2_MIPS_EABI
-	default o64		if BR2_MIPS_OABI64
-	default 64		if BR2_MIPS_ABI64
+	default n32		if BR2_MIPS_NABI32
+	default 64		if BR2_MIPS_NABI64
 	default mmixware	if BR2_mmix && BR2_MMIX_ABI_native
 	default gnu		if BR2_mmix && !BR2_MMIX_ABI_native
 	default altivec		if BR2_powerpc && BR2_PPC_ABI_altivec
diff --git a/toolchain/uClibc/uclibc.mk b/toolchain/uClibc/uclibc.mk
index 9d0b6db..aff0a60 100644
--- a/toolchain/uClibc/uclibc.mk
+++ b/toolchain/uClibc/uclibc.mk
@@ -38,6 +38,7 @@  UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
 		-e 's/sh[234].*/sh/' \
 		-e 's/mips.*/mips/' \
 		-e 's/mipsel.*/mips/' \
+		-e 's/mips64el.*/mips/' \
 		-e 's/cris.*/cris/' \
 		-e 's/xtensa.*/xtensa/' \
 ")
@@ -45,6 +46,8 @@  UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
 UCLIBC_TARGET_ENDIAN:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
 		-e 's/armeb/BIG/' \
 		-e 's/arm/LITTLE/' \
+		-e 's/mips64el/LITTLE/' \
+		-e 's/mips64/BIG/' \
 		-e 's/mipsel/LITTLE/' \
 		-e 's/mips/BIG/' \
 		-e 's/sh.*eb/BIG/' \
@@ -155,13 +158,13 @@  ifeq ($(UCLIBC_TARGET_ARCH),mips)
 	 /bin/echo "# CONFIG_MIPS_ISA_MIPS32R2 is not set"; \
 	 /bin/echo "# CONFIG_MIPS_ISA_MIPS64 is not set"; \
 	) >> $(UCLIBC_DIR)/.oldconfig
-ifeq ($(BR2_MIPS_OABI),y)
+ifeq ($(BR2_MIPS_OABI32),y)
 	$(SED) 's/.*\(CONFIG_MIPS_O32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
 endif
-ifeq ($(BR2_MIPS_ABI32),y)
+ifeq ($(BR2_MIPS_NABI32),y)
 	$(SED) 's/.*\(CONFIG_MIPS_N32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
 endif
-ifeq ($(BR2_MIPS_ABI64),y)
+ifeq ($(BR2_MIPS_NABI64),y)
 	$(SED) 's/.*\(CONFIG_MIPS_N64_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
 endif
 ifeq ($(BR2_mips_1),y)