Subject: Re: Proposed extension to bus.h interface
To: Mike Long <>
From: Jason Thorpe <>
List: tech-kern
Date: 08/27/1996 20:44:55
On Thu, 15 Aug 96 18:25:02 EDT 
 Mike Long <> wrote:

 > If the desired application of bus_io_{alloc,free}() is P&P I/O range
 > allocation, then bus_io_alloc() needs three more pieces of
 > information:
 > 1) minimum address (port)
 > 2) maximum address (port)
 > 3) number of address bits decoded (10 or 16)

Hmm ... probably what I'll do is implement isa_pnp_alloc(), or something 
along those lines ... there's quite a discussion about how to handle i/o 
vs. mem mapped stuff ... it looks like the bus.h interface is going to 
see some sweeping changes RSN (to merge the two spaces into a common 
handle, to facilitate easier writing of MI drivers...)

 > The minimum and maximum addresses would also be useful for
 > bus_mem_alloc().  10-bit decoding is a silly ISA-bus artifact, so it's
 > only needed for I/O allocation.

The "start", "end", and "don't cross this boundary" arguemnts have been a 
common request :-)

 > BTW, how does your extent system handle 10-bit I/O decoding now?  Does
 > it just assume that any I/O port ranges in the [0,0x3ff] range use
 > 10-bit decoding?

Err, the extent manager literally just mucks with extents of space, and 
knows nothing about the underlying encoding... You're the first person to 
bring this up, actually :-)

 -- save the ancient forests - -- 
Jason R. Thorpe                             
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