In light of the recent talk about macros, I had a little play with
converting the macros in <mips/bus_space.h> to functions in a new
file (mips/mips/bus_space.c).

To pick on example, in <mips/bus_space.h> instead of:

	#define bus_space_read_1(t, h, o) \
		__bs_rs(1,uint8_t,(t),(h),(o))

there's now:

	u_int8_t  bus_space_read_1(bus_space_tag_t, \
		bus_space_handle_t, bus_size_t);

(line wraps for this email) and bus_space.c has:

	u_int8_t
	bus_space_read_1(bus_space_tag_t space,
	    bus_space_handle_t handle, bus_size_t offset)
	{

		return __bs_rs(1,uint8_t,space,handle,offset);
	}

For an evbmips/malta kernel, the old and new kernels are:

       text    data     bss     dec     hex filename
    1948008  177488   61732 2187228  215fdc netbsd.old
    1913432  177488   61732 2152652  20d8cc netbsd.new

For an evbmips/pb1000 kernel, the savings are a bit less since there's
fewer drivers that use bus_space functions:

   text    data     bss     dec     hex filename
2304760  210736   74536 2590032  278550 netbsd.old
2292904  210736   74536 2578176  275700 netbsd.new

To pick a benchmark at random, building tcsh over NFS on an pb1500 board
(which uses bus_space functions in it's ethernet driver) before took:

    350.520u 44.351s 6:58.84 94.2%  0+0k 0+0io 185pf+0w
    349.663u 44.458s 6:59.13 94.0%  0+0k 0+0io 7pf+0w
    349.797u 44.109s 6:56.85 94.4%  0+0k 0+0io 7pf+0w

and after took:

    351.099u 44.318s 6:58.40 94.5%  0+0k 0+0io 112pf+0w
    351.480u 43.919s 6:57.58 94.6%  0+0k 0+0io 7pf+0w
    351.205u 44.174s 6:54.45 95.3%  0+0k 0+0io 7pf+0w

So we've saved about 35kB of text for one kernel, about 12kB for another
and any performance changes are statistical noise.  Obviously including
more bus_space aware drivers in a kernel is going to increase any more
space savings too.

Diffs for this are at
   ftp://ftp.NetBSD.org/pub/NetBSD/misc/simonb/mips.bus_space.diff

I can't think of a reason not to apply this patch.  Can anyone else?

Simon.
--
Simon Burge                                   <simonb@wasabisystems.com>
NetBSD Development, Support and Service:   http://www.wasabisystems.com/