Re: Over 2.5 GB ram problem

[Gary Roach <gary719_list1@verizon.net>]

On 07/10/2013 02:53 PM, Joel Rees wrote:

On Thu, Jul 11, 2013 at 1:47 AM, Gary Roach <gary719_list1@verizon.net> wrote:

On 07/09/2013 11:40 PM, Greg Madden wrote:

On Tuesday 09 July 2013 13:46:05 you wrote:

I just upgraded my old Intel P4 system with a 3Ghz multithread (2
processors?) processor and 4 GB ram. I am running Debian Wheezy with
a KDE desktop. My  present kernel is Linux-3.8-1=686-pae. From
reading, I think I need to change the kernel to the bigmem version
but all of the packages shown are for much older versions (or they
seem to be). If I install the linux-image-686-bigmem dummy package
will it automatically pick the latest kernel version or not? If not
what do I do?

Note: Reason for doing this; cheap used parts that turn a bucket of
bolts into a reasonably useful system.

Gary R.

old naming=bigmem, new naming=pae, both the same.

Now I am really confused. I have two systems; one with an Intel P4, 3GHz, multi-thread and one with an Intel i5-750. Both are running Wheezy with a KDE desktop. The i5-750 system recognizes the 4GB of memory but the P4 system does not. They are both running "pae" kernels.

My impression is that the P4 is likely to be a 32 bit cpu. P4s may or may not have the hardware extensions that allow (bank-switch) access to memory beyond the 4G boundary (2G on some systems).

Is your i5-750 a 32 bit cpu or 64 bit? My memory is that there are some intel "core" series cpus that were 32 bit. But those would all be recent enough to include the "bigmem" or pae hardware extensions in the cpu.

But I think the i5 is likely to be 64 bit, anyway. (And the 32 bit pae kernel includes the "magic" that allows the 32 bit mode to access memory above the 32 bit boundary.)

 

The Kinfocenter shows that the P4 system is running a Linux 3.2.0-4-686-pae kernel and the Aptitude listing agrees. The i5-750 system Kinfocenter shows a Linux 3.8-1-686-pae kernel but the Aptitude listing shows a Linux 3.2.0-4-686-pae kernel installed. Further, in the the layout of the firmware-linux package in Aptitude, the P4 system list it in kernel / main and the i5-750 system list it in kernel / non-free.

What is going on here?

Gary R.

No idea about Kinfocenter, but the hardware on a motherboard can definitely include stuff that the manufacturer refuses to release developer specs without an NDA, if at all. Older motherboards tend to have better workarounds, found by reverse-engineering.

--
Joel Rees

First, i believe that Kinfocenter is showing the version of the linux-image-686-pae dummy package and not the actual kernel version. One problem solved.

Second, you are right. The i5-750 is a 64 bit processor. But the documentation for the pae enabled kernel specifically lists all of the Intel P series processors as compatible. Ergo, the P4 should be able to access well over 4GB of ram. So what is wrong?

Gary R.