I have a question about adding a device to ARM VM linux. When a device is
added to the vmlinux, two functions, map_device () and map_ram () are
invoked. I don't understand the purpose of map_ram().
In map_device(), the capacity to the device is used to set up the mapping
between a virtual address and the MMIO (of the device). Then, in the
map_ram (), a capacity to the virtual address is allocated. I am confused
because the virtual address is already mapped to the mmio of the device.
why do we need to allocate a capacity for the virtual address? Should the
capacity be the same as the one for the device?
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