2GB address space limit on 32-bit PowerPC Macintosh

Dan Malek dan at embeddededge.com
Tue May 17 06:31:01 EST 2005

On May 16, 2005, at 2:06 PM, Mark A. Greer wrote:

> Oops...
> /me unintentionally stepped into the middle of a flame war  :)

Just pee on it :-)

> To be clear, "offender" == board that has an io_block_mapping below 
> the 3 GB line.

That is one of the obvious changes. You are likely to find some other 
that may need attention.  The problem with io_block_mapping is you just 
remove it, you have to fix up all of the code that is based on the 
assumption these
spaces are mapped.  You are likely to find yourself in a situation 
where you need
access to some board control registers before VM is set up and you can 
ioremap().  So, you will find yourself doing some hack in head.S to map 
registers to get access to this, which is exactly what 
io_block_mapping() does,
only in a way that is obvious :-)


	-- Dan

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