svn commit: r183896 - head/sys/dev/bge

[M. Warner Losh]

In message: <48F5053D.7070705 at samsco.org>
            Scott Long <scottl at samsco.org> writes:
: Marius Strobl wrote:
: > Author: marius
: > Date: Tue Oct 14 20:28:42 2008
: > New Revision: 183896
: > URL: http://svn.freebsd.org/changeset/base/183896
: > 
: > Log:
: >   Use bus_{read,write}_4(9) instead of bus_space_{read,write}_4(9)
: >   in order to get rid of the bus space handle and tag in the softc.
: >   
: 
: Has anyone looked at the generated code from this interface switch and
: compared it what was getting generated previously?  Way back when,
: including <machine/bus_memio.h> made bus_space_read|write_4() compile
: into a direct memory access on machines that supported it.  The dubious
: removal of bus_memio.h and bus_pio.h took away that benefit, and I'm
: afraid that it's only getting worse now.  Bus writes to card memory are
: still very important to high-performance devices and shouldn't be
: pessimized in the name of simpler-looking C code.

I've looked a little.  With changes similar to this change, the
generated code does look better because there's less stack traffic,
but it still isn't a direct write to memory without a function call...

Warner