Adding a MACHINE_ARCH note

[Peter Wemm]

On Tue, Jul 9, 2013 at 5:56 PM, Adrian Chadd <adrian at freebsd.org> wrote:
> ... boy I'd like to see this particular x86 hiccup fixed before this
> stuff is mainstream.

I'm not entirely sure how much support there is behind "x32".  I don't
know if its much more than an academic curiosity or if there's real
demand for it.  gcc-4.8 and clang have it, or have patches for it.

https://sites.google.com/site/x32abi/

http://www.phoronix.com/scan.php?page=news_item&px=MTExNDE


> adrian
>
> On 9 July 2013 17:54, Peter Wemm <peter at wemm.org> wrote:
>> On Tue, Jul 9, 2013 at 5:40 PM, Adrian Chadd <adrian at freebsd.org> wrote:
>>> Someone pointed out there's dirty people running 32-bit binaries using
>>> the 64-bit intel/amd instruction set.
>>>
>>> Is this also able to represent that?
>>
>> That would be "X32", so there's 3 x86 ABI variants:
>> i386 - 32 bit
>> amd64 - 32 bit
>> amd64 - 64 bit
>>
>> Incidentally, pkgng has a issues with this.  For some reason it lumps
>> both i386 and amd64 into a single pseudo-arch called "x86" with a 32
>> and 64 bit variant.  It doesn't leave room for distinguishing the two
>> incompatible 32 bit architectures.
>>
>> "x32" is where the compiler generates code where "long" and "pointer"
>> are 32 bit, but the instruction set is otherwise amd64 and has all 16
>> general purpose registers available.   "long long" is a 64 bit
>> register instead of a pair of 32 bit registers like on i386.
>>
>>> -adrian
>>>
>>> On 9 July 2013 15:48, Andrew Turner <andrew at fubar.geek.nz> wrote:
>>>> On Tue, 9 Jul 2013 08:19:46 -0600
>>>> Warner Losh <imp at bsdimp.com> wrote:
>>>>> I thought that the ELF headers gave us all the data we needed to know
>>>>> how things were built...
>>>>
>>>> It will tell us if it was for e.g. an ARM or MIPS ELF file, but I'm not
>>>> sure how we can tell the difference between an arm and an armv6 ELF.
>>>>
>>>> With armv6 there are a few changes in the userland/kernel
>>>> interface, e.g. reading the thread local storage pointer is different
>>>> such that an armv6 static binary would not run on an ARMv5 core as it
>>>> uses newer instructions.
>>>>
>>>> Andrew
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>>
>>
>>
>> --
>> Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com; KI6FJV
>> UTF-8: So you can \342\200\231 .. for when a ' just won't do
>> <brueffer> ZFS must be the bacon of file systems. "everything's better with ZFS"



-- 
Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com; KI6FJV
UTF-8: So you can \342\200\231 .. for when a ' just won't do
<brueffer> ZFS must be the bacon of file systems. "everything's better with ZFS"