[Buildroot] [PATCH v2] Disable o32 ABI for MIPS64 architectures
Vicente Olivert Riera
Vincent.Riera at imgtec.com
Wed Mar 26 14:24:47 UTC 2014
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 at 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
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