Re: Why :O?

[Jim Wise <jwise%draga.com@localhost>]

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On Tue, 17 Jun 2008, Alan Barrett wrote:

>On Mon, 16 Jun 2008, der Mouse wrote:
>> In the 4.0 sys/conf/Makefile.kern.inc, I find
>> 
>> SYSTEM_DEP?=    Makefile ${SYSTEM_OBJ:O} .gdbinit
>> 
>> Why is the :O there?
>
>See the log message from the change that added the :O, and another
>similar change nearby:
>
>----------------------------
>revision 1.76
>date: 2006/04/19 07:08:17;  author: lukem;  state: Exp;  lines: +2 -2
>Order & uniq DEPS, a la <bsd.dep.mk>.
>----------------------------
>revision 1.75
>date: 2006/04/19 07:06:22;  author: lukem;  state: Exp;  lines: +2 -2
>Sort SYSTEM_OBJ before adding to SYSTEM_DEP.
>Kernel builds are now more consistent with userland
>(and IMHO building in order is more asthetically pleasing.)
>----------------------------

Hmm.  IIRC, the reason this change was made in userland was so that all 
the variants of a single file (.ln, .o, .po, .so, etc) would be built in 
order, maximizing cache hits.  The aesthetics, of course, followed 
nicely therefrom.

It sounds like this change to the kernel builds is actually hurting 
cacheability, by jumping back and forth from directory to directory.

Or am I missing something?

- -- 
                                Jim Wise
                                jwise%draga.com@localhost
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