FreeBSD/arm64 MACHINE/MACHINE_ARCH identification

Nathan Whitehorn nwhitehorn at freebsd.org
Thu Feb 12 18:44:55 UTC 2015


On 02/12/15 10:37, Warner Losh wrote:
>
>> On Feb 12, 2015, at 10:58 AM, Nathan Whitehorn
>> <nwhitehorn at freebsd.org> wrote:
>>
>> On 02/12/15 09:15, Ed Maste wrote:
>>>>> Oh - I don't care what directory Linux puts the kernel source
>>>>> in, only what's reported by uname.  As far as I can tell that
>>>>> has always been aarch64 for uname -m.
>>>>
>>>> Traditionally in Linux, they have been a matched set.
>>>
>>> Ok, it appears they may have abandoned this.
>>>
>>>>> We might decide that "uname -m" has to be aarch64 to match
>>>>> expectations of third-party software set by other operating
>>>>> systems. If that in turn means we have to move the kernel
>>>>> source, so be it.
>>>>
>>>> This one I’m not on board with. You’ve not made a compelling
>>>> case for it yet.
>>>
>>> That's why I said "we might decide" -- I'm not sure myself.
>>>
>>> However, there's no backwards compatibility concern here, we've
>>> never had a FreeBSD release that reports "arm64" for "uname -m".
>>> There's no reason for us to prefer "arm64" if everyone else uses
>>> "aarch64." Also, having arm64 for uname -m and aarch64 for uname
>>> -p seems a bit odd.
>>
>> I would assume uname -m would be "arm", not "arm64". Unless there
>> are fundamental platform differences you are baking in somehow,
>> which I don't know.
>
> arm would be a pleasing outcome, but looking at his WIP tree, it
> looks like it would be possible, but rather inconvenient to merge the
> arm64 bits back under arm and make them conditional.
>
> Warner
>
>


That's unfortunate. Among other things, it precludes easy use of cc 
-m32. So what is the long-term plan here? Is the new ARM port a new, 
legacy-free, version that should grow separate 32-bit support for new 
armv7 systems and then we abandon sys/arm to the ARMv5 stuff? Or are 
32-bit and 64-bit ARM just going to live separate lives forever?
-Nathan


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