On Fri, Aug 12, 2011 at 8:17 AM, Jan Beulich <jbeul...@novell.com> wrote: >>>> On 12.08.11 at 16:47, "H.J. Lu" <hjl.to...@gmail.com> wrote: >> On Fri, Aug 12, 2011 at 7:42 AM, Jan Beulich <jbeul...@novell.com> wrote: >>>>>> On 12.08.11 at 16:02, "H.J. Lu" <hjl.to...@gmail.com> wrote: >>>> On Fri, Aug 12, 2011 at 6:59 AM, Jan Beulich <jbeul...@novell.com> wrote: >>>>>>>> On 12.08.11 at 15:22, "H.J. Lu" <hjl.to...@gmail.com> wrote: >>>>>> On Fri, Aug 12, 2011 at 6:17 AM, Jan Beulich <jbeul...@novell.com> wrote: >>>>>>>>>> On 12.08.11 at 14:09, "H.J. Lu" <hjl.to...@gmail.com> wrote: >>>>>>>> On Fri, Aug 12, 2011 at 12:30 AM, Jan Beulich <jbeul...@novell.com> >>>>>>>> wrote: >>>>>>>>>>>> On 12.08.11 at 06:37, "H.J. Lu" <hjl.to...@gmail.com> wrote: >>>>>>>>>> On Mon, Aug 1, 2011 at 3:15 PM, H.J. Lu <hjl.to...@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. >>>>> >>>>> For a constant that has more than 32 significant bits??? >>>>> >>>> >>>> Can you give me an example in assembly code? >>> >>> Something like >>> >>> .equ sym, 0x1234567890 >>> .global sym >>> >> >> "sym" is truncated to 32bit: > > Yes, because of your tying of the ABI to ELF32.
X32 uses ELF32 and won't change. >> Symbol table '.symtab' contains 5 entries: >> Num: Value Size Type Bind Vis Ndx Name >> 0: 00000000 0 NOTYPE LOCAL DEFAULT UND >> 1: 00000000 0 SECTION LOCAL DEFAULT 1 >> 2: 00000000 0 SECTION LOCAL DEFAULT 2 >> 3: 00000000 0 SECTION LOCAL DEFAULT 3 >> 4: 34567890 0 NOTYPE GLOBAL DEFAULT ABS sym >> >> However, one can write >> >> .quad main + 0x8000000 > > And I suppose that wouldn't work either with your R_X86_64_64 > implied zero-extension... > I will investigate. -- H.J.
