windows - Why is this memory range on the PCI bus?

07
2014-07
  • RJSmith92

    Why is the following memory address range on the PCI bus?

    enter image description here

    The image is from my Netbook that uses shared video memory with no dedicated video memory so I am unsure as to why the VGA memory range would be on the PCI bus. Wouldn't this range need to go to system memory which then the PCI device reads from?

    This isn't an issue but rather just curiosity as to why it is.

    Any help would be appreciated.

    Thanks.

    • Answers
  • David Schwartz

    Your graphics adapter doesn't have literally no dedicated memory at all. If it did, how would it know what it was in the middle of doing? If it was, for example, operating from a particular area of main memory, how would it know which area of main memory that was or what it was using it for? This is a very small mapping for the exchange of control information between the GPU and CPU. It is implemented as a very small amount of special function memory on the GPU, made visible to the CPU through a PCI memory mapping.

    This is basically the same way it's done if the GPU does have dedicated memory, except the mapping would typically be larger. Though, generally, it doesn't include all of the video memory -- there's no need for that. Small windows into the video memory are sufficient.


    • Related Question

    Installing a PCI-E graphics card when the onboard VGA port is not working
  • dhasu

    Previously I had asked a question abt monitor/VGA port problems. Today finally i came to a conclusion that the VGA port on my motherboard is broken.

    The solution is find is to buy a PCI-E VGA card , a cheaper option.

    OR

    Buy a Graphics Card, I prefer this one as VGA Card manufacturers aren't quite standard.

    I want to know if the graphic cards we get today are plug and play? Should I disble the onboard VGA port before installing a Graphics card. If the VGA port isnt working in the first place (the monitor wont start) how should i do it ? All i need is how to install a Graphics card when the onboard VGA port isnt working.

    Also suggest me a graphics card, I just need a Port for my monitor, I dont need high performance.


    • Related Answers
  • markfknight

    Depends, usually the bios will be set-up to use the PCI-E as an override, so you will be able to plug in the Graphics card and attach a monitor and it will work. You will not have the best resolution until the correct drivers have been installed for the card, so install once Windows boots.

    If you have set you bios to only run from the onboard graphics and you cannot get the bios on your monitor, refer to your motherboard manual in regards to resetting you bios as the defaults should allow for the detection of the PCI-E card.