The HCDP table is one (non-proprietary) way for the platform to
inform the OS about headless operation. This field would normally
hold the address as can be found by scanning the EFI system table,
which we also pass to the kernel. The apparent duplication allows
us to synthesize a HCDP table in the loader by whatever means we
can think of, including relocating the platform table into pre-
mapped address space. In short: it gives us more freedom.
Approved by: re (blanket)
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