Date: Mon, 23 Sep 1996 13:54:40 +1000 From: Bruce Evans <bde@zeta.org.au> To: msmith@atrad.adelaide.edu.au, terry@lambert.org Cc: brandon@glacier.cold.org, freebsd-hackers@FreeBSD.org, jgreco@brasil.moneng.mei.com Subject: Re: splash-page on bootup.. Message-ID: <199609230354.NAA03404@godzilla.zeta.org.au>
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>> This is only because we are stupid and use DELAY() instead of a >> calibrated timer list of one-shot outcall functions. Using a >> spinloop is just inherently stupid. > >Uh? You are still thinking like a CS guy, not a hardware programmer. > >When I am looking for some hardware in a probe routine, I want _nothing_ >_nada_ _zip_ happening behind my back. No interrupts, no "strategically >placed callbacks", nothing. > >This has nothing to do with how DELAY() works, it's basic 'least surprise' >stuff. Yes, DELAY() works like it does because it must work at probe time before timer interrupts are enabled. DELAY() shouldn't be used at other times except for very short delays (short = about the same time as it takes to initialize a one-shot timer and service a one-shot timer interrupt (10-50 usec). OTOH, probes in lkm'ed drivers can timer expect interrupts to work, and shouldn't use DELAY() or otherwise hog the cpu any more than the driver would for normal operations. Bruce
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