The x86 version is basically just a specialization of the base IO port
version of the QEMU firmware configuration device, with the port
addresses set for x86.
The E820 entry type is x86 specific, and is a way to pass an E820 memory
map to firmware which doesn't have another way to figure out where
memory is. This would be for firmware like SeaBIOS which is itself
responsible for publishing an E820 map, but it needs somewhere to get
that information from in the first place. This mechanism is one it
supports natively.
This entry type reuses the E820Entry SimObjects which were defined a
long time ago for passing to a Linux FS workload. It doesn't use their
ability to write themselves out to guest memory, and just uses them as a
transport for their address, size and type properties.
Change-Id: Ifff214f5fc10bd7d0a2a0acddad4fc00dd65f67d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55628
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
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