The full RSDP is useful beyond just extracting the RSDT address out of it. In particular
this prepares us for being able to pass a copy of the RSDP to the rootserver.
The previous function signature might lead a user to believe that they were getting a
pointer to a useable acpi_rsdt_t structure. This was in fact not the case and was
actually returning the physical address, that may or may not be mapped in, of the rsdt
table. All of the other acpi *_scan functions would therefore immediately map in the physical
rsdt pointer they were given.
This commit changes acpi_init to return a boolean indicating whether it found a valid
rsdp, and then fills in a copy of the rsdp data. The copy is necessary as the rsdp
data may be at a temporary mapping.
As a result of changing acpi_init the boot code and state is changed to have a acpi_rsdt_t
instance that can be filled out.
ee380609c6