Subject: pmap
To: None <amiga-dev@sun-lamp.cs.berkeley.edu>
From: None <newsham@uhunix.uhcc.Hawaii.Edu>
List: amiga-dev
Date: 03/20/1994 09:33:06
I'm a bit confused about one detail in the pmap and vm system. There
are two page sizes defined, PAGE_SIZE = 4096 and AMIGA_PAGE_SIZE = 8192.
When the kernel steals pages for its own use it seems to be grabbing
AMIGA_PAGE_SIZE sized chunks. atop() which should convert an address
into pages does a >> page_size, page_size is initialized to 12 by the
vm system (2^12 = 4096).
One of the things I have to do to use MACHINE_NONCONTIG is to make routines
reporting how many pages left and another routine to pass the address
of the next page. Should I be using PAGE_SIZE and atop() or should
I be handing out AMIGA_PAGE_SIZE pages and using >> 13 to get the number
of pages?
What is the purpose of the two different page sizes?
Tim N.
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