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To: KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp>
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Subject: Re: cvs commit: src/sys/i386/isa/sound sb.h src/sys/pc98/conf GENERIC98 Makefile.pc98 options.pc98 src/sys/pc98/i386 locore.s machdep.c pmap.c userconfig.c vm_machdep.c src/sys/pc98/pc98/sound ad1848.c os.h pas2_pcm.c sb16_dsp.c ulaw.h sb.h src/sys/pc98/boot/biosboot boot.c boot.h disk.c io.c sys.c table.c src/sys/pc98/pc98 atcompat_diskslice.c clock.c diskslice_machdep.c if_ed.c if_ed98.h if_fe.c npx.c pc98.c pc98.h pc98_machdep.c pc98_machdep.h pcaudio.c random_machdep.c sbic55.c sbic55.c.new sio.c syscons.c syscons.h wd.c 
In-reply-to: Your message of "Thu, 10 Oct 1996 13:05:07 +0900."
             <199610100405.NAA05067@marble.eps.nagoya-u.ac.jp> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Thu, 10 Oct 1996 04:42:37 -0700
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>On Thu, 10 Oct 1996 08:19:59 +1000, Bruce Evans <bde@zeta.org.au> said:
>
>> >  (7) Do not expect bss to be zero-allocated:
>> >  
>> >  	pc98/pc98/pc98.c
>> 
>> This should be expected.
>
>I think kernel is expected to initialize bss, but programer should not 
>expect this because I consider bss to non initialized data.

   As far as FreeBSD is concerned, you should always expect that behavior.
The entire system is based on the assumption that .bss variables are zero
initialized, and if they weren't we'd have serious problems. Initializing
variables to any value (including 0) only serves to move them out of the .bss
and into statically allocated space...and thus bloats your kernel binary 
more than necessary.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project