Re: Extending boot protocol & bzImage for paravirt_ops

H. Peter Anvin
2007-06-01T21:57:31Z

Jeremy Fitzhardinge wrote:
> H. Peter Anvin wrote:
>>> Do we care particularly? If 8 bytes is enough for the subarch, do we
>>> care whether its a pointer or literal? After all, this is just a private
>>> channel between the bootloader and some subarch-specific piece of code
>>> in the kernel.
>>>
>>>
>> I see two options: either we make it a pointer *and a length* so that a
>> loader can reshuffle it at will (that also implies no absolute pointers
>> within the data), or it's an opaque cookie anyway.
>
> No, it has to be completely opaque. It might be a pointer to some
> special shared memory or something, and not movable.
>

Well, if we define is as a movable object then it has to be treated as
such. It's a protocol definition issue. If we define it opaque, though
-- of for that matter, if we don't -- we should define what memory it
can live in, though. Right now, the only "available" memory we have is
end of setup to 0xa0000; the command line is defined to be allocated
from this memory.

-hpa