Subject: Re: bus space macros for structures
To: Michael Richardson <>
From: Jason Thorpe <>
List: tech-kern
Date: 02/03/1997 17:10:45
On Mon, 3 Feb 1997 19:40:48 -0500 (EST) 
 Michael Richardson <> wrote:

 >   I take it that the bus macros mean that one should *not* map a
 > structure to
 > shared ram? Assume that the structure has two definitions based on
 > endianness.
 >   I should, to achieve maximum portability, bus_read/bus_write all
 > I/O to shared
 > memory?

That is correct; structures are not portable for a couple of reasons,
one of them being byte order, the other being packing...

You should access the device using only offsets in bus_space_* calls.

(Arguably, we should do the same thing with e.g. SCSI CDBs.)

Jason R. Thorpe                             
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