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Re: [x32] Allow R_X86_64_64


On Fri, Aug 12, 2011 at 6:17 AM, Jan Beulich <JBeulich@novell.com> wrote:
>>>> On 12.08.11 at 14:09, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>> On Fri, Aug 12, 2011 at 12:30 AM, Jan Beulich <JBeulich@novell.com> wrote:
>>>>>> On 12.08.11 at 06:37, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>>>> On Mon, Aug 1, 2011 at 3:15 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>> Hi,
>>>>>
>>>>> It turns out that x32 needs R_X86_64_64. ?One major reason is
>>>>> the displacement range of x32 is -2G to +2G. ?It isn't a problem
>>>>> for compiler since only small model is required for x32.
>>>>>
>>>>> However, to address 0 to 4G directly in assembly code, we have
>>>>> to use R_X86_64_64 with movabs. ?I am checking the follow patch
>>>>> into x32 psABI to allow R_X86_64_64.
>>>>>
>>>>>
>>>>
>>>> X32 ?Linker should treats R_X86_64_64 as R_X86_64_32
>>>> zero-extended to 64bit for output. ?I will update x32 psABI with
>>>
>>> I'm sorry to say that, but the situation about x32 seems to be
>>> getting worse with each change you do, every time again
>>> revolving around mixing up ABI specification and a particular
>>> implementation thereof.
>>>
>>> Here, if you need something zero-extended (though I can't see
>>> why you would), then you should use a new relocation type. As
>>> pointed out before, there are valid possible uses of R_X86_64_64
>>> that would require the semantics of x86-64.
>>>
>>
>> When does x32 need the semantics of x86-64 for R_X86_64_64?
>
> When referencing an assembler or linker defined constant that
> exceeds 32-bit in width. Given that this is a 64-bit architecture
> with 32-bit addresses, at least I would expect such to work.
>

Yes, it should work just fine for x32 by zero-extending 32bit
address to 64bit.

-- 
H.J.


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