Some PCIe devices cannot read more than 4 GB of address space without an additional driver or modified driver. In such cases, what limits how much memory they can read? Is it the memory controller? Is it the firmware of the PCIe device? Or is it something else? I don't think it is because of the device driver itself because PCIe devices can read or write to RAM without a driver. Someone said to me that it is a 32-bit vs 64-bit issue but I do not understand why PCIe device can only address 32-bit.
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What OS? What device? When I hear about a hard 4 GB (or 3 GB, or 2 GB) limit of addressable memory, the immediate thing that comes to mind is the limit that OSes and CPU / memory controllers got over by switching from 32 to 64 bit addressing. – Christopher Hostage Dec 27 '19 at 18:43
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@ChristopherHostage The device and the OS are not relevant. I am wondering if anything in the memory controller or BIOS can decide whether or not a device can read more than 4 GB of memory, in such a way that even an additional driver cannot make the device read more than 4 GB of memory. – Joe Toe Dec 27 '19 at 23:25