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.
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
The info for AMD will be here. (http://sourceware.org/binutils/docs-2.18/as/index.html)
I see a IA-64 section in that link but the only AMD section I saw was for 3D Now.
Does IA-64 = AMD64 ?
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.
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 ?
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.
Quote
--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 (http://sourceware.org/binutils/docs-2.18/binutils/objcopy.html#objcopy) may be able to convert between object file formats.
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.
Maybe you would like to give nasm a try?
http://nasm.sourceforge.net
It's somewhat 'nicer' than GAS :U
Not to go OT but I much rather prefer GAS to Nasm.
Got any specific reasons?
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.
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:
Quote 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
I'm sorry you need all that. a.out is all I need. :toothy
Well GAS can do 64bit got that figured out.
(-64 switch and specify the arch)
But will there be a hiccup with ld ?
The docs for the linker show that the only 64 bit arch it supports is PowerPC64.
QuoteGAS syntax annoys me pretty bad.
So use the .intel directive to make it just like masm
Is it possible to work with GAS using the masm systaxis?
Could you tell me where I can download all the necessary to start work with GAS?
Thanks,
GUAN
Yeah, you can use the intel directive like James posted to get masm like syntax.
Right now I am trying to get the linker ld to link 32bit code on a 64bit machine.
I know that sounds kinda weird but some tools and libraries I have are still 32bit and though I can run those programs on AMD64 but I can't build anything. I can get as to compile the code but ld won't link (I specify a 32bit target but ld says it can't either find it or warns me that I am on a 64bit platform).
FWIW, I posted a set of (32-bit) invoke macros for GAS here (http://www.masm32.com/board/index.php?topic=8689.0), and I noticed at the Binutils link that a new version was released on December 12.
My particular problem is using as/ld to compile 32bit code on a AMD64 Xubuntu machine.
All the code and libraries I have are for 32bit, AMD64 has a compatiblity mode to execute 32 applications but I can't compile them.
So I can run 32bit applications but have no means to continue to develop them.
I can get as to compile 32bit code but I can't get ld to link them.
This works:
as --32 something.s something.o
None of these do:
ld --oformat elf32_i386 something.o
ld --oformat a.out-i386-linux something.o
ld --oformat i386linux something.o
Wouldn't you use the -m switch for ld?
32bit: –m elf_i386
64-bit: –m elf_x86_64
I am basing this on info from AMD's 64-bit linux support page:
http://developer.amd.com/documentation/articles/pages/914200640.aspx
I am not familiar with emulation in linkers.
To me emulation means to 'pretend', like how emulators on your pc 'pretend' to be another machine.
I was trying to get real 32bit code.
I'll try the -m switch in ld and see what happens.
(That works, I can compile but when I try to run program bash reports that permission is denied. Assuming it means file permissions I have permission to read/write and execute)
If the current problem is converting object modules between formats, Agner Fog has a tool for that:
http://www.agner.org/optimize/#objconv
I am not converting any object code.
(All the following is done on an AMD 64 machine)
I assembled 32 bit code using "as --32"
I linked that object into executable using "ld -m elf_i386"
And then I tried to execute the app.
The error I get is that permission is denied.
Arrg, this is getting kinda frustrating.
I can finally get as to compile 32 bit code and ld to link 32 bit on a 64 bit processor but the application won't execute.
bash keeps telling me that permission is denied, (but permissions are set right)
Are there other permissions ??
How are you suppose to compile 32 bit code when manufacturers are changing over to multi-core 64 bit machines ?
Here is what I got so far. I have gotten farther from my original question at least but not all the way there yet.
I can build 32 bit code with as (using --32)
I can link 32 bit code with ld (using -m elf_i386 and -m i386linux)
But it will not execute. (I attached readelf output for -m elf_i386)
The error I get is permission denied, which is wierd because I have rwx permissions for that directory and file.
I am not working on anything in particular, I am just trying to build the examples from the Programming from the Ground Up book to figure out how to build 32bit code on amd64.
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If you dont like GAS syntax, then use the Intel directive and - presto ! - you can do away with
all the %%ages :)
I don't have a particular issue with syntax, unless as is producing something that ld doesn't like.
Compiling and linking "appear'' to work but no 32bit app I build will run on a 64bit machine.