Re: [patch 2.6.27-rc7] i2c: smbalert# support

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

Hi Trent,

On Sat, 22 Nov 2008 12:28:56 -0800 (PST), Trent Piepho wrote:
> On Sat, 22 Nov 2008, Jean Delvare wrote:
> > On Fri, 21 Nov 2008 22:04:26 -0800 (PST), Trent Piepho wrote:
> >> The size of i2c-core, struct i2c_client and struct i2c_adapter:
> >> v2.6.28 9718 392 500	w/ smbalert patch
> >> v2.6.28 8878 392 472
> >> v2.6.27 8732 368 448
> >> v2.6.26 7877 352 440
> >> v2.6.25 7854 376 444
> >> v2.6.24 9060 372 444
> >> v2.6.23 9359 404 476
> >> v2.6.22 9330 448 520
> >> v2.6.21 7814 464 692
> >> v2.6.20 7896 444 672
> >> v2.6.19 7871 444 668
> >> v2.6.18 6857 436 660
> >
> > Thanks for providing these numbers, these are really useful! I'm
> > curious if you would be able to compute the same numbers down to, say,
> > kernel 2.6.5 or even 2.6.0? I'm curious where we started from.
> >
> > I am also interested in the script / method you used to come up with
> > these numbers, so that maybe I can get the numbers myself if you do not
> > have the time.
> 
> It's not entirely automatic since you have to deal with configuring the
> kernel.  It helps to start at the newest kernel and work backwards, since
> kconfig options are added more often than removed.
> 
> I put this in my .bashrc to make getting object sizes easier:
> function objsize { ${CROSS_COMPILE}objdump -h $1 | awk '/text|data|bss/{x=strtonum("0x"$3);printf "%-16s%d\t%d\n",$2,x,s+=x;}' ;}

Not sure why you don't just use "size" for this?

> Then to get structure sizes:
> cat > lib/size.c
> #include <linux/i2c.h>
> #define S(t) cpu_to_be32(sizeof(struct t))
> uint32_t a=S(i2c_adapter), b=S(i2c_client);  // reverse order in obj
> 
> On older kernels you have to replace cpu_to_be32() with ___constant_swab32()
> on little-endian systems and remove it on big-endian.
> 
> Then do this for each version:
> 
> ver=v2.6.17
> git checkout -f $ver
> echo 'obj-y += size.o' >> lib/Makefile
> mkdir $ver
> cp last.config $ver/.config
> make O=$ver
> # answer make questions, try not to turn on anything that adds debug/trace
> # code or extra fields to data structures.  Or turns off extra fields that
> # used to be mandatory.  Or changes compiler flags, e.g. inlining or regparm. 
> # Wait...
> ssize=`objdump -s -j .data $ver/lib/size.o |
>  	awk '/^ 0/{print strtonum("0x"$2),strtonum("0x"$3);}'`
> csize=`objsize $ver/drivers/i2c/i2c-core.o | awk 'END{print $3}'`
> echo `git describe` $csize $ssize >> i2csize
> cp $ver/.config last.config
> 
> v2.6.17 6934 416 640
> v2.6.16 7320 404 620

Hmm, OK, that's not exactly trivial... I don't think I'll have the time
to setup this.

Given that you already have everything in place, would you please
provide the additional numbers I am interested in? No need to do all
kernel versions down to 2.6.0, you certainly have more interesting
things to do with your time. All I am really interested in are 2.6.5
and 2.6.0. This should give us a good idea of where we started from.

Thanks,
-- 
Jean Delvare