AMD64 GAS Documtentation ?

[DarkWolf]

I have an AMD Athlon X2, would anyone know where to find information for 64 bit assembly ?

This is an Xubuntu box so I am looking for GAS documentation.
I am not that worried about dual-core just yet, I can deal with that later.

[farrier]

DarkWolf,

Look at the fasm, flatassembler.net  Open source, liberal license, very powerful!

Actively developed and supported 32/64 bit assembler for DOS, Windows, Linux and other nixes, Solaris, and other.

hth,

farrier

[drhowarddrfine]

The info for AMD will be here.

[DarkWolf]

I see a IA-64 section in that link but the only AMD section I saw was for 3D Now.

[DarkWolf]

Does IA-64 = AMD64 ?

[Ghirai]

No, ia64 reffers to Intel Itanium architecture, whereas amd64 reffers to the x86-64 architecture (Intel's implementation name was EMT64T, now Intel 64 afaik).
Most likely you would want the amd64 docs.

So IA-64 != AMD64 :bg

I'd add that you would normally find Itanium CPUs in enterprise-grade servers, not in desktops.

[DarkWolf]

I asked because the only 64 bit info I could find in drhowarddrfine's link was Intel's.

Trial and error, I can't even get a pop()/push() instruction to work on an AMD64 X2

Has anyone else tried Gas assembly on an AMD64 ?

[MichaelW]

There doesn't appear to be very many things that are x86-64 specific.

http://sourceware.org/binutils/docs-2.18/as/i386_002dDependent.html#i386_002dDependent

The ability to select a 64-bit word size only for the ELF object file format would seem to be a serious impediment to x86-64 development for Windows.

--32 | --64
Select the word size, either 32 bits or 64 bits. Selecting 32-bit implies Intel i386 architecture, while 64-bit implies AMD x86-64 architecture.

These options are only available with the ELF object file format, and require that the necessary BFD support has been included (on a 32-bit platform you have to add enable-64-bit-bfd to configure enable 64-bit usage and use x86-64 as target platform).

Edit:

Perhaps not, it looks like objcopy may be able to convert between object file formats.

[DarkWolf]

That's more complicated than what I was hoping to find.

If I could get Gas to compile the source converting the obj code might be an idea, but I am having trouble getting it to compile on this machine.

I am not sure where my difficulty lies, am I using a 32 bit Gas on a AMD64 machine ?
Man page says there is a IA-64 switch but I can't find that section in the man page.
There are x86_64 scripts listed in the binutils package for ld (linker)

Ah Ha,
Found more information in the info page for as.
There is a --64 switch for the i386 verison that will assemble for x86_64 arch.

I'll have to check it out more.

[Ghirai]

Maybe you would like to give nasm a try?
http://nasm.sourceforge.net

It's somewhat 'nicer' than GAS :U

[drhowarddrfine]

Not to go OT but I much rather prefer GAS to Nasm.

[Ghirai]

Got any specific reasons?

[drhowarddrfine]

I was afraid you would ask that but it's been a long time since I compared.  One is that I can seamlessly work between my OS, all the gcc languages and assembly.  If you bring up the syntax issue then it's a non-issue for me.  I have zero problems with it.

[Ghirai]

Good for you, GAS syntax annoys me pretty bad.

I like NASM because of the syntax, and because it outputs in quite a few formats:

    bin       flat-form binary files (e.g. DOS .COM, .SYS)
    aout      Linux a.out object files
    aoutb     NetBSD/FreeBSD a.out object files
    coff      COFF (i386) object files (e.g. DJGPP for DOS)
    elf32     ELF32 (i386) object files (e.g. Linux)
    elf       ELF (short name for ELF32)
    elf64     ELF64 (x86_64) object files (e.g. Linux)
    as86      Linux as86 (bin86 version 0.3) object files
    obj       MS-DOS 16-bit/32-bit OMF object files
    win32     Microsoft Win32 (i386) object files
    win64     Microsoft Win64 (x86-64) object files
    rdf       Relocatable Dynamic Object File Format v2.0
    ieee      IEEE-695 (LADsoft variant) object file format
    macho     NeXTstep/OpenStep/Rhapsody/Darwin/MacOS X object files

Also last time i checked GAS docs were pretty thin, might have changed though.

Sorry for the OT, just having a conversation, i don't intend to start an assembler flamewar :bg

[drhowarddrfine]

I'm sorry you need all that.  a.out is all I need.   :toothy