svn commit: r266553 - head/release/scripts

[Tijl Coosemans]

On Sat, 24 May 2014 09:04:33 -0700 Nathan Whitehorn wrote:
> On 05/24/14 07:59, Tijl Coosemans wrote:
>> On Fri, 23 May 2014 17:29:48 -0600 Warner Losh wrote:
>>> On May 23, 2014, at 10:20 AM, Baptiste Daroussin <bapt at FreeBSD.org> wrote:
>>>> On Fri, May 23, 2014 at 08:52:28AM -0700, Nathan Whitehorn wrote:
>>>>> On 05/23/14 08:36, Baptiste Daroussin wrote:
>>>>>> On Fri, May 23, 2014 at 08:19:34AM -0700, Nathan Whitehorn wrote:
>>>>>>> Is there any chance of finally switching the pkg abi identifiers to just
>>>>>>> be uname -p?
>>>>>>> -Nathan
>>>>>> Keeping asking won't make it happen, I have explained a large number of time why it
>>>>>> happened, why it is not easy for compatibility and why uname -p is still not
>>>>>> representing the ABI we do support, and what flexibility we need that the
>>>>>> current string offers to us.
>>>>>>
>>>>>> if one is willing to do the work, please be my guess, just dig into the archives
>>>>>> and join the pkg development otherwise: no it won't happen before a while
>>>>>> because we have way too much work on the todo and this item is stored at the
>>>>>> very end of this todo.
>>>>>>
>>>>>> regards,
>>>>>> Bapt
>>>>> I'm happy to do the work, and have volunteered now many times. If uname
>>>>> -p does not describe the ABI fully, then uname -p needs changes on the
>>>>> relevant platforms. Which are they? What extra flexibility does the
>>>>> string give you if uname -p describes the ABI completely?
>>>>> -Nathan
>>>> just simple examples in armv6:
>>>> - eabi vs oabi
>>>> - The different float abi (even if only one is supported for now others are
>>>>   being worked on)
>>>> - little endian vs big endian
>>> All of those are encoded in the MACHINE_ARCH + freebsd version, no exceptions
>>> on supported architectures that are tier 2 or higher. This seems like a weak reason.
>>>
>>>> the extras flexibilit is being able to say this binary do support freebsd i386
>>>> and amd64 in one key, freebsd:9:x86:*, or or all arches freebsd:10:*
>>> Will there be a program to convert this new, special invention to the standard
>>> that we’ve used for the past 20 years? If you need the flexibility, which I’m not
>>> entirely sure I’ve seen a good use case for. When would you have a x86 binary
>>> package? Wouldn’t it be either i386 or amd64?
>> ABI isn't just about the instruction set.  It's also about the sizes of C
>> types (like pointers).  If I remember correctly, the pkg scheme was chosen
>> to allow for ABIs like x32 which use the 64 bit instruction set with 32
>> bit pointers.  MACHINE_ARCH would also be amd64 in this case.
> 
> No, it wouldn't. MACHINE_ARCH would be something else (x32, probably) in 
> such cases. MACHINE_ARCH (and uname -p, which reports it) is the FreeBSD 
> ABI identifier and encodes 100% of the ABI information. This would be 
> true even if there is never an x32 kernel.

No, there's no such thing as an x32 kernel.  It's an amd64 kernel that
supports a second userland ABI.  In C preprocessor terms they are
distinguished by (__amd64__ && _LP64) and (__amd64__ && !_LP64).
uname -p gives you the processor architecture (the __amd64__ bit) but
then you can still choose the sizes of standard C types (the _LP64 bit).
So far we've always had one ABI per processor architecture but this
is not strictly necessary.