[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Axel Lin]

Current setting only allows blackfin to select uclinux as TARGET_OS.
However, some noMMU ARM platforms that using FLAT binary format also need to
select uclinux as TARGET_OS. Fix the dependency.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
---
I need this change to allow testing build for ARM noMMU.
Maybe worth to upstream.

Axel
 package/Makefile.in | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/package/Makefile.in b/package/Makefile.in
index 91ae1b9..6aa6266 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -23,8 +23,8 @@ MAKE:=$(HOSTMAKE) -j$(PARALLEL_JOBS)
 # Compute GNU_TARGET_NAME
 GNU_TARGET_NAME=$(ARCH)-buildroot-$(TARGET_OS)-$(LIBC)$(ABI)
 
-# Blackfin FLAT needs uclinux
-ifeq ($(BR2_bfin)$(BR2_BINFMT_FLAT),yy)
+# FLAT binary format needs uclinux
+ifeq ($(BR2_BINFMT_FLAT),y)
 TARGET_OS=uclinux
 else
 TARGET_OS=linux
-- 
1.8.1.2

[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Axel Lin]

Some noMMU ARM platforms need to select BR2_BINFMT_FLAT.
Most ARM platforms have MMU, thus set default to BR2_BINFMT_ELF for ARM.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
---
 arch/Config.in | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/Config.in b/arch/Config.in
index 14899ca..31c23ec 100644
--- a/arch/Config.in
+++ b/arch/Config.in
@@ -223,8 +223,9 @@ config BR2_GCC_TARGET_MODE
 # Set up target binary format
 choice
 	prompt "Target Binary Format"
-	depends on BR2_bfin || BR2_m68k
-	default BR2_BINFMT_FDPIC
+	depends on BR2_arm || BR2_bfin || BR2_m68k
+	default BR2_BINFMT_ELF if BR2_arm
+	default BR2_BINFMT_FDPIC if (BR2_bfin || BR2_m68k)
 
 config BR2_BINFMT_ELF
 	bool "ELF"
@@ -245,7 +246,7 @@ config BR2_BINFMT_FDPIC
 
 config BR2_BINFMT_FLAT
 	bool "FLAT"
-	depends on BR2_bfin || BR2_m68k
+	depends on BR2_arm || BR2_bfin || BR2_m68k
 	select BR2_PREFER_STATIC_LIB
 	help
 	  FLAT binary is a relatively simple and lightweight executable format
-- 
1.8.1.2

[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Thomas Petazzoni]

Dear Axel Lin,

On Wed, 04 Sep 2013 10:44:27 +0800, Axel Lin wrote:

> diff --git a/arch/Config.in b/arch/Config.in
> index 14899ca..31c23ec 100644
> --- a/arch/Config.in
> +++ b/arch/Config.in
> @@ -223,8 +223,9 @@ config BR2_GCC_TARGET_MODE
>  # Set up target binary format
>  choice
>  	prompt "Target Binary Format"
> -	depends on BR2_bfin || BR2_m68k
> -	default BR2_BINFMT_FDPIC
> +	depends on BR2_arm || BR2_bfin || BR2_m68k
> +	default BR2_BINFMT_ELF if BR2_arm
> +	default BR2_BINFMT_FDPIC if (BR2_bfin || BR2_m68k)

I know it was broken before, but FDPIC isn't supported on BR2_m68k, so
I guess we should have something like:

	prompt "Target Binary Format"
	depends on BR2_arm || BR2_m68k || BR2_bfin
	default BR2_BINFMT_ELF if BR2_arm
	default BR2_BINFMT_FDPIC if BR2_bfin
	default BR2_BINFMT_FLAT if BR2_m68k

But I'm wondering if we shouldn't go further than that, and make
BR2_BINFMT_FLAT available only for non-MMU ARMs. Something like:

	prompt "Target Binary Format"
	depends on BR2_arm7tmdi || BR2_arm_cortex_m3 ||	BR2_arm_cortex_m4 || BR2_m68k || BR2_bfin
	default BR2_BINFMT_FLAT if BR2_arm7tmdi || BR2_arm_cortex_m3 ||	BR2_arm_cortex_m4 || BR2_m68k
	default BR2_BINFMT_FDPIC if BR2_bfin

or something like this. This way, users of MMU-capable ARM variants
wouldn't be confused by the availability of FLAT and ELF as binary
formats. Of course, BR2_BINFMT_ELF should gain some !BR2_arm7tmdi
&& !BR2_arm_cortex_m3 && !BR2_arm_cortex_m4 dependencies, or maybe even
a !BR2_USE_MMU dependency. I think there's quite some room for
improvement around the definition of which CPU has an MMU or not, and
which architectures support which binary formats.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Thomas De Schampheleire]

Op 5-sep.-2013 23:48 schreef "Thomas Petazzoni" <
thomas.petazzoni@free-electrons.com> het volgende:

> But I'm wondering if we shouldn't go further than that, and make
> BR2_BINFMT_FLAT available only for non-MMU ARMs. Something like:
>
>         prompt "Target Binary Format"
>         depends on BR2_arm7tmdi || BR2_arm_cortex_m3 || BR2_arm_cortex_m4
|| BR2_m68k || BR2_bfin
>         default BR2_BINFMT_FLAT if BR2_arm7tmdi || BR2_arm_cortex_m3 ||
BR2_arm_cortex_m4 || BR2_m68k
>         default BR2_BINFMT_FDPIC if BR2_bfin
>
> or something like this. This way, users of MMU-capable ARM variants
> wouldn't be confused by the availability of FLAT and ELF as binary
> formats. Of course, BR2_BINFMT_ELF should gain some !BR2_arm7tmdi
> && !BR2_arm_cortex_m3 && !BR2_arm_cortex_m4 dependencies, or maybe even
> a !BR2_USE_MMU dependency. I think there's quite some room for
> improvement around the definition of which CPU has an MMU or not, and
> which architectures support which binary formats.

Don't we/shouldn't we have something like ARCH_HAS_MMU and/or
ARCH_SUPPORTS_FLAT_BINARY?

Best regards,
Thomas
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[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Thomas Petazzoni]

Dear Thomas De Schampheleire,

On Fri, 6 Sep 2013 03:08:10 +0200, Thomas De Schampheleire wrote:

> > or something like this. This way, users of MMU-capable ARM variants
> > wouldn't be confused by the availability of FLAT and ELF as binary
> > formats. Of course, BR2_BINFMT_ELF should gain some !BR2_arm7tmdi
> > && !BR2_arm_cortex_m3 && !BR2_arm_cortex_m4 dependencies, or maybe even
> > a !BR2_USE_MMU dependency. I think there's quite some room for
> > improvement around the definition of which CPU has an MMU or not, and
> > which architectures support which binary formats.
> 
> Don't we/shouldn't we have something like ARCH_HAS_MMU and/or
> ARCH_SUPPORTS_FLAT_BINARY?

Yes, we should probably have something like this (and ditto for other
binary formats: ELF, FDPIC and so on).

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Gustavo Zacarias]

On 09/06/2013 03:25 AM, Thomas Petazzoni wrote:

> On Fri, 6 Sep 2013 03:08:10 +0200, Thomas De Schampheleire wrote:
> 
>> Don't we/shouldn't we have something like ARCH_HAS_MMU and/or
>> ARCH_SUPPORTS_FLAT_BINARY?
> 
> Yes, we should probably have something like this (and ditto for other
> binary formats: ELF, FDPIC and so on).

On a side note, remember that HAS_MMU doesn't mean it's using it - from
what i've read you can use MMU-bearing processors to test uclinux
MMU-less scenarios (dunno if it can be done with every SOC out there,
probably depends on the linux support for each one, at least a couple of
Atmel ones were used this way for testing and/or masochism).
Regards.

[Buildroot] [PATCH 2/2] arch/Config.in: Allow ARM to select BR2_BINFMT_FLAT

[Thomas Petazzoni]

Dear Gustavo Zacarias,

On Fri, 06 Sep 2013 07:08:16 -0300, Gustavo Zacarias wrote:
> On 09/06/2013 03:25 AM, Thomas Petazzoni wrote:
> 
> > On Fri, 6 Sep 2013 03:08:10 +0200, Thomas De Schampheleire wrote:
> > 
> >> Don't we/shouldn't we have something like ARCH_HAS_MMU and/or
> >> ARCH_SUPPORTS_FLAT_BINARY?
> > 
> > Yes, we should probably have something like this (and ditto for other
> > binary formats: ELF, FDPIC and so on).
> 
> On a side note, remember that HAS_MMU doesn't mean it's using it - from
> what i've read you can use MMU-bearing processors to test uclinux
> MMU-less scenarios (dunno if it can be done with every SOC out there,
> probably depends on the linux support for each one, at least a couple of
> Atmel ones were used this way for testing and/or masochism).

Right. We could distinguish what the hardware is capable of (i.e
BR2_HAS_MMU vs. !BR2_HAS_MMU) and what the user wants to do
(BR2_USE_MMU vs. !BR2_USE_MMU). Of course, BR2_USE_MMU depends on
BR2_HAS_MMU. That said, until now, we've been hiding BR2_USE_MMU on
many architectures for which !MMU doesn't exist/isn't supported. On
ARM, I believe it doesn't make much sense to expose !MMU for
MMU-capable variants.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Thomas Petazzoni]

Dear Axel Lin,

On Wed, 04 Sep 2013 10:43:18 +0800, Axel Lin wrote:
> Current setting only allows blackfin to select uclinux as TARGET_OS.
> However, some noMMU ARM platforms that using FLAT binary format also need to
> select uclinux as TARGET_OS. Fix the dependency.

Are you sure uclinux as TARGET_OS is the right selection for ARM? The
release notes of gcc 4.7, at http://gcc.gnu.org/gcc-4.7/changes.html,
indicate:

""
The obsolete ports with alternatives are:

    arm*-*-rtems (use arm*-*-rtemseabi)
    arm*-*-linux-gnu (use arm*-*-linux-gnueabi)
    arm*-*-elf (use arm*-*-eabi)
    arm*-*-uclinux* (use arm*-*-uclinux*eabi)
""

So it looks like the arm-<something>-uclinux* tuple should not be used,
if I understand this correctly. Do you have more details about why
arm-<something>-uclinux* should be used?

Thanks!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Axel Lin]

2013/9/6 Thomas Petazzoni <thomas.petazzoni@free-electrons.com>:
> Dear Axel Lin,
>
> On Wed, 04 Sep 2013 10:43:18 +0800, Axel Lin wrote:
>> Current setting only allows blackfin to select uclinux as TARGET_OS.
>> However, some noMMU ARM platforms that using FLAT binary format also need to
>> select uclinux as TARGET_OS. Fix the dependency.
>
> Are you sure uclinux as TARGET_OS is the right selection for ARM? The
> release notes of gcc 4.7, at http://gcc.gnu.org/gcc-4.7/changes.html,
> indicate:
>
> ""
> The obsolete ports with alternatives are:
>
>     arm*-*-rtems (use arm*-*-rtemseabi)
>     arm*-*-linux-gnu (use arm*-*-linux-gnueabi)
>     arm*-*-elf (use arm*-*-eabi)
>     arm*-*-uclinux* (use arm*-*-uclinux*eabi)
> ""
>
> So it looks like the arm-<something>-uclinux* tuple should not be used,
> if I understand this correctly. Do you have more details about why
> arm-<something>-uclinux* should be used?

Somehow, I thought noMMU ARM platforms that using FLAT binary format needs to
select uclinux as TARGET_OS.
But since you mentioned the release notes of gcc 4.7, I'm not 100% sure.

I check my build, the result is I have arm-buildroot-uclinux-uclibcgnueabi-gcc.
And the build log shows it checks target system type as:
checking target system type... arm-buildroot-uclinux-uclibcgnueabi

Does buildroot automatically convert arm*-*-uclinux* to arm*-*-uclinux*eabi?

I also check host-gcc-final-4.5.4/gcc/config.gcc and libgcc/config.host.
Looks like it also expects arm*-*-uclinux* for ARM ucLinux and arm*-*-linux* for
ARM GNU/Linux with ELF.

Thanks for the review,
Axel

[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Thomas Petazzoni]

Dear Axel Lin,

On Fri, 6 Sep 2013 10:21:55 +0800, Axel Lin wrote:

> > So it looks like the arm-<something>-uclinux* tuple should not be used,
> > if I understand this correctly. Do you have more details about why
> > arm-<something>-uclinux* should be used?
> 
> Somehow, I thought noMMU ARM platforms that using FLAT binary format needs to
> select uclinux as TARGET_OS.
> But since you mentioned the release notes of gcc 4.7, I'm not 100% sure.

I am not sure either.

> I check my build, the result is I have arm-buildroot-uclinux-uclibcgnueabi-gcc.
> And the build log shows it checks target system type as:
> checking target system type... arm-buildroot-uclinux-uclibcgnueabi
> 
> Does buildroot automatically convert arm*-*-uclinux* to arm*-*-uclinux*eabi?
> 
> I also check host-gcc-final-4.5.4/gcc/config.gcc and libgcc/config.host.
> Looks like it also expects arm*-*-uclinux* for ARM ucLinux and arm*-*-linux* for
> ARM GNU/Linux with ELF.

Can you check in more recent gcc versions such as 4.7 or 4.8 ? Looking
at the most recent versions is important to see what is the current
tuple accepted for this situation.

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [PATCH 1/2] package/Makefile.in: Fix dependency for selecting uclinux as TARGET_OS

[Axel Lin]

2013/9/6 Thomas Petazzoni <thomas.petazzoni@free-electrons.com>:
> Dear Axel Lin,
>
> On Fri, 6 Sep 2013 10:21:55 +0800, Axel Lin wrote:
>
>> > So it looks like the arm-<something>-uclinux* tuple should not be used,
>> > if I understand this correctly. Do you have more details about why
>> > arm-<something>-uclinux* should be used?
>>
>> Somehow, I thought noMMU ARM platforms that using FLAT binary format needs to
>> select uclinux as TARGET_OS.
>> But since you mentioned the release notes of gcc 4.7, I'm not 100% sure.
>
> I am not sure either.
>
>> I check my build, the result is I have arm-buildroot-uclinux-uclibcgnueabi-gcc.
>> And the build log shows it checks target system type as:
>> checking target system type... arm-buildroot-uclinux-uclibcgnueabi
>>
>> Does buildroot automatically convert arm*-*-uclinux* to arm*-*-uclinux*eabi?
>>
>> I also check host-gcc-final-4.5.4/gcc/config.gcc and libgcc/config.host.
>> Looks like it also expects arm*-*-uclinux* for ARM ucLinux and arm*-*-linux* for
>> ARM GNU/Linux with ELF.
>
> Can you check in more recent gcc versions such as 4.7 or 4.8 ? Looking
> at the most recent versions is important to see what is the current
> tuple accepted for this situation.

Hi Thomas,
In host-gcc-final-4.8.1/gcc/config.gcc:

# Unsupported targets list.  Do not put an entry in this list unless
# it would otherwise be caught by a more permissive pattern.  The list
# should be in alphabetical order.
case ${target} in
 # Avoid special cases that are not obsolete
   arm*-*-*eabi*                        \
 )
        ;;
   arm*-wince-pe*                       \
 | arm*-*-ecos-elf                      \
 | arm*-*-elf                           \
 | arm*-*-freebsd*                      \
 | arm*-*-linux*                        \
 | arm*-*-uclinux*                      \
 | i[34567]86-go32-*                    \
 | i[34567]86-*-go32*                   \
 | m68k-*-uclinuxoldabi*                \
 | mips64orion*-*-rtems*                \
 | pdp11-*-bsd                          \
 | sparc-hal-solaris2*                  \
 | thumb-*-*                            \
 | *-*-freebsd[12] | *-*-freebsd[12].*  \
 | *-*-freebsd*aout*                    \
 | *-*-linux*aout*                      \
 | *-*-linux*coff*                      \
 | *-*-linux*libc1*                     \
 | *-*-linux*oldld*                     \
 | *-*-rtemsaout*                       \
 | *-*-rtemscoff*                       \
 | *-*-solaris2                         \
 | *-*-solaris2.[0-8]                   \
 | *-*-solaris2.[0-8].*                 \
 | *-*-sysv*                            \
 | vax-*-vms*                           \
 )
        echo "*** Configuration ${target} not supported" 1>&2
        exit 1
        ;;
esac

The first case shows
case ${target} in
 # Avoid special cases that are not obsolete
   arm*-*-*eabi*                        \
 )
        ;;

Although I have no idea which part of buildroot system converts
arm*-*-uclinux* to arm*-*-uclinux*eabi.
The build result shows arm-buildroot-uclinux-uclibcgnueabi which matches
the first case.
So I think it's ok to set TARGET_OS=uclinux.

Regards,
Axel