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Re: why 1G memory is missing?

On 03.08.21 18:26, IL Ka wrote:

    inxi shows that only 3 GB are available as the TOTAL, although it finds
    the 4 GB to be physically installed:
    $ sudo inxi -m -x
    Memory:    RAM: total: 2.88 GiB used: 2.11 GiB (73.2%)
    Array-1: capacity: 4 GiB slots: 2 EC: None max module size: 2 GiB
    note: est.
    Device-1: M1 size: 2 GiB speed: 667 MT/s type: DDR2
    Device-2: M2 size: 2 GiB speed: 667 MT/s type: DDR2
It could be a different problem (Windows may calculate RAM differently in different places, where did you check it?). I'd start with a memory map (see Sven Hartge's comment in this thread), also see https://en.wikipedia.org/wiki/E820 <https://en.wikipedia.org/wiki/E820> 
A similar tool for Windows is "Rammap".
With 32bit system you would never be able to use 4GB (because part of address space is used for MMIO by PCI-(express) devices). With 64bit address space is much larger, but some ram is used by kernel. Some tools exclude such ram.
Although the original question got a valid answer already, in this case the chipset did not support 4 GB and not even a 64bit OS, I here add to some sub-part of the thread (see above in this email what I am referring to) some information for completeness - I got time to search in old threads on the German spoken Debian mailing list where this topic was also up some time ago.
Sven Hartge pointed out and explained that the missing 1 GB on a 64 bit system could be related to what is called the "PCI hole" and also the following link was provided: 

https://en.wikipedia.org/wiki/PCI_hole
I wasn't able to understand all technical explanations by Sven Hartge, neither everything what's published in the wikipedia article, this all is obviously a topic for real hardware experts, but it at least convinced me that it should not be a configuration failure in my Debian installation - however, why MS Windows on the identical hardware shows the full 4 GB to be available never became clear to me.
Saying all this, I will not be able to further discuss this topic here in this thread as I am for far too large extend not understanding the necessary basics, but at least wanted to leave this information about the "PCI hole". 

Always stay in good spirits, Marco!
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