[Buildroot] [PATCH v2] Disable o32 ABI for MIPS64 architectures

[Vicente Olivert Riera <Vincent.Riera@imgtec.com>]

On 03/26/2014 02:19 PM, Markos Chandras wrote:
> On 03/26/2014 12:14 AM, Joshua Kinard wrote:
>> On 03/25/2014 16:02, Arnout Vandecappelle wrote:
>>> On 25/03/14 18:52, Vicente Olivert Riera wrote:
>>>> Building o32 ELF files for MIPS64 is an exotic configuration that
>>>> nobody
>>>> should be using. If o32 is required, then is better if it's built for
>>>> MIPS 32-bit cores so only 32-bit instructions will be used leading to a
>>>> more efficient o32 usage.
>>>>
>>>> Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
>>>> ---
>>>>   arch/Config.in.mips |   12 +++++++-----
>>>>   1 files changed, 7 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/arch/Config.in.mips b/arch/Config.in.mips
>>>> index d9c0c02..f558705 100644
>>>> --- a/arch/Config.in.mips
>>>> +++ b/arch/Config.in.mips
>>>> @@ -38,15 +38,12 @@ endchoice
>>>>
>>>>   choice
>>>>       prompt "Target ABI"
>>>> -    depends on BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el
>>>> -    default BR2_MIPS_OABI32 if !BR2_ARCH_IS_64
>>>> -    default BR2_MIPS_NABI32 if BR2_ARCH_IS_64
>>>> +    depends on BR2_mips64 || BR2_mips64el
>>>> +    default BR2_MIPS_NABI32
>>>>
>>>>       help
>>>>         Application Binary Interface to use
>>>>
>>>> -config BR2_MIPS_OABI32
>>>> -    bool "o32"
>>>>   config BR2_MIPS_NABI32
>>>>       bool "n32"
>>>>       depends on BR2_ARCH_IS_64
>>>> @@ -86,6 +83,11 @@ config BR2_GCC_TARGET_ARCH
>>>>       default "mips64"    if BR2_mips_64
>>>>       default "mips64r2"    if BR2_mips_64r2
>>>>
>>>> +config BR2_MIPS_OABI32
>>>> +    bool
>>>> +    default y        if BR2_mips || BR2_mipsel
>>>> +    default n        if BR2_mips64 || BR2_mips64el
>>>
>>>   The default n isn't needed - that is the default already in all
>>> other cases.
>>>
>>>> +
>>>>   config BR2_GCC_TARGET_ABI
>>>>       default "32"        if BR2_MIPS_OABI32
>>>>       default "n32"        if BR2_MIPS_NABI32
>>>>
>>>
>>>   Normally we should have a Config.in.legacy entry to catch old .configs
>>> that have o32 for a mips64 target. However, that is not possible now.
>>> Therefore, it should be captured in the release notes. To make sure that
>>> Peter doesn't forget, can you add this to the top of CHANGES?
>>>
>>>
>>> 2014.05, Not yet released:
>>>
>>> Support for MIPS o32 ABI on MIPS-64 targets has been removed. Building
>>> o32 ELF files for MIPS64 is an exotic configuration that nobody
>>> should be
>>> using. If o32 is required, then is better if it's built for MIPS 32-bit
>>> cores so only 32-bit instructions will be used leading to a more
>>> efficient o32 usage.
>>
>> Just to point out, I wouldn't call this "exotic" -- o32 on mips64 kernels
>> (MIPS-IV ISA) is what I run on my SGI O2 under Gentoo.  That said, I
>> do have
>> a somewhat-working n32 chroot on the same box.  Additionally, isn't
>> o32 the
>> ABI that Debian still builds for most of their mips/mipsel targets?
>
> We are talking about using 64-bit instructions in *userland* while
> maintaining the o32 ABI semantics. Well, this is definitely an exotic
> configuration. We are not talking about 64-bit kernels + o32 userland.
> An o32 userland usually comes from mips32 and you usually have only
> 32-bit instructions there.
>

V3 sent: http://patchwork.ozlabs.org/patch/333959/

-- 
Vincent