machine 32 or 64 bts?
 

Can i tell if my computer is 32 bits or 64 bits?
It looks like the below result says that it is 32 b, but i installed Ubuntu x86_64 version. It seems to work fine. will there be any problem for doing so?

Since the 64 bit OS is running, it's a good sign that your machine is 64bit capable.

I don't see a 64bit flag on your CPU info though :scratch: where I would expect to see something like x86_64 or em64t or similar...

Do you by chance have the "dmidecode" tool? Try the following commands:

shell# /usr/sbin/dmidecode

or

shell# /sbin/dmidecode

and look for something like "64-bit capable" in the output.

It may also be helpful to tell us what exact model of CPU you have, and the motherboard you're running.

Sasha

PS - the above output is not what one would expect from the "uname -a" command.. uname -r should tell you what kernel you're running though.

uname -i should tell you the hardware platform. But, first and foremost, you cannot run 64-bit stuff on a 32-bit system. Thus, you have a 64-bit system.

By the by, that doesn't look like any uname -a output I've ever seen. Looks more like cat /proc/cpuinfo

Yes. The output you quoted shows your CPU is 64 bit.

That is an even more certain way to know your CPU is 64 bit.

I think you messed up your copy/paste. You showed us the uname -a command but not its output and you showed us the contents of /proc/cpuinfo. I assume you intended to show both.

That line tells you it is 64 bit. Notice the lm (meaning "long mode") that I highlighted.

That line also tells you your cpu is 64 bit.

All 32 bit x86 cpu's have 32 bit virtual addressing. All current x86-64 cpus have 48 bit virtual addressing. Future 64 bit cpus are expected to have more than 48 bit addressing.

The physical address size is more varied by CPU model. A 32 bit cpu could have 36 bit physical addresses. Apparently a 64 bit cpu also can have 36 bit physical addresses (I think typical 64 bit cpus have 38 or more bits physical address).

Stated perfectly, if the installer and OS runs it's 64 bit. It's impossible to run 64bit code on a 32bit platform, though you can always (well 99.9%) run 32bit on 64bit due how they created the cpu's. In reality they could make the cpu 64bit only but I don't think that's going to come for a while yet.

Thanks Johnsfine -- always something new to learn around here, every day!

Intel made some goofy motherboards for a while. The CPU was 64bit but the memory controller was only 32bit. Which meant that you could run a 64bit OS but you were stuck with the 32bit memory limit(roughly 3.2 GB). I am GUESSING that is what the "address sizes : 36 bits physical" may be hinting at. All of which means that you are fine unless you need to upgrade your memory beyond 3.2GB and even then I may be wrong in my interpretation of the 36bit stuff.

No, I think the 36 bits physical is correct...

I think Intel does there 64bit extentions different than AMD. If you want to get technical neither are pure 64 bit as they run an emulation layer, but by 'definition' they are both 64 bit.

http://www.flexbeta.net/forums/lofiv...php/t5534.html

The address size is probably in refrence to the amount of RAM supported...

I do think he can go over 3.2G of ram as that would probably be 32bit physical if I'm not mistaken.

"address sizes : 36 bits physical" calculates to 64GB. That probably means it's PAE compatible. But, who's to know until they install the OS? :)

The 36 bits refers to the address that the CPU sends to the memory controller. In an Intel design, that doesn't necessarily tell you the size of the address the memory controller receives from the CPU. The CPU might send 36 bits, but the memory controller might only listen to 32 bits (giving you the three point something GB limit of physical ram).

All the x86_64 CPUs are compatible with 32 bit PAE. A 36 bit physical address probably means they haven't change the interface between the CPU and memory controller that was used for earlier 32 bit chips. But other x86-64 chips with more physical address bits are still compatible with 32 bit PAE. You just don't get to use the extra bits (beyond 36) when the OS is 32 bit PAE.

You can define "pure 64 bit" to make that statement true or false. Either way, it isn't a particularly meaningful statement.

That is more fundamentally false (though one can always distort the meaning of words far enough to make such statements true).

http://www.flexbeta.net/forums/lofiv...php/t5534.html

Almost all the posts near the top of that thread are nonsense as clearly explained by some one the later posts.

That is also pretty solidly false.

I'm not certain of the xp64 memory limit in x86-64 architecture. I think it is less than the limit in x86-64 architecture itself (which is less than 64 bit). But it certainly is not more than the architecture limit.

The chipset I was referring to is Intel 945GM.

Edit: http://en.wikipedia.org/wiki/List_of...2Fx4x_Chipsets

lm on the flags is the main indicator. You have it, so you should be good to go 64 bit.

flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow up rep_good

Sorry about the mem limit:


http://en.wikipedia.org/wiki/X86-64
I don't know if the math is correct or not, but I'm guessing that's where the 40 and 36 play into effect.

The 36-bit relates to PSE36. PSE36 is similar or PAE, but the memory pages for PSE36 assignment is 4 KiB for the first 4 GiB of RAM and using memory above 4 GiB uses 8 KiB pages. It is nothing do with the processor if it can execute 64-bit instructions.

The utility dmidecode is not good as lshw of telling what hardware you have and its capabilities. I suggest lshw because it is thoroughly when looking up data about your computer.

That seems reasonable, as PAE can probably address the same amount of RAM which then you really can't just assume it's 64bit because of how much ram it uses. =S