From mboxrd@z Thu Jan 1 00:00:00 1970 From: C Subject: Re: 32 bit processors / 64 bit processors Date: Thu, 22 Oct 2009 22:20:54 -0700 Message-ID: References: <7783925d0910202002ubcd5328nd8c82bb11e5f84ea@mail.gmail.com> <9b0a5b990910202239u7423e88du4786700f79a4bda9@mail.gmail.com> <49FAB6BD-25CD-484D-AC5D-4731D083E075@gmail.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=k+tfFpRx8ufK5YP3BMW7o3AUUMG9IqwxBT5aTfpQwPo=; b=mBWzcU7IGuknmIdDNRyLbpcagn78WDnLc9WtOy3U3KJtpqdZ3fMrH/nNCWlRVHDedV O0gRezpwJvtXJXJUSz+dRqIBTI2+FIUqthOz+sX/+RcEHD7UwWVog9S6yhswrqKQ4rN/ dvEPuqKxh1Q1v0v9bnwKo7n3k4V8ZcoSCVEeQ= In-Reply-To: Sender: linux-newbie-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Rajat Jain Cc: simonyanix@gmail.com, Siddu , Rick Brown , kernelnewbies , linux-newbie@vger.kernel.org PAE (Physical Address Extension) expands the _physical_ address space to > 32 bits, but the _virtual_ address space stays the same at 32-bits, and the virtual address size is what I mentioned as qualifies the processor as 32-bit or 64-bit. 1. Addressable physical memory / physical address size does not decide whether a processor is 32-bit / 64-bit, there is no processor (AFAIK) which can address 64 bits of physical memory. I suppose sizeof(void*) gives you the size of the _virtual_ address, so yes, I suppose that should be 64 bits on a 64-bit processor (and using a 64-bit compiler) 2. Register size does not decide whether a processor is 32-bit / 64-bit. C On Thu, Oct 22, 2009 at 10:05 PM, Rajat Jain wrote: > > Hi, > >> 1. The size of the processor's internal address bus (virtual address >> space) is what qualifies it as a 32-bit / 64-bit processor. > > Well, in that sense, isn't Pentium a "36-bit" processor (since it gives > the option of PAE to use 64 GB of memory - it must be having atleast 36 > address lines)? > > On this topic and in this thread, we have had following responses to the > question on what is called a 32-bit or 64-bit processor: > > 1) Addressable Physical memory (=sizeof(void*)) > 2) Register Size (=instruction size) > > Are the above two independent of each other? If yes, then how do we > deine a processor as 32-bit / 64-bit? > > Thanks, > > Rajat > > -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs