On Mon, Sep 21, 2015 at 12:03:29PM -0400, Kevin O'Connor wrote:
According to my Intel docs, PAE supports the same 52bit physical address range that x86_64 supports.
Thinking about this further, I could see changing SeaBIOS' 32bit code to always use PAE mode (when available). Doing so would enable support for PCI devices mapped above 64bit (there is already a USB exception in pciinit.c because of this). It would mean implementing ioremap and teaching malloc and the drivers to use it, but that seems doable. A simple PAE ioremap implementation could use 2MB pages exclusively which would reduce complexity.