Date: Mon, 28 Jul 1997 22:07:00 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, msmith@atrad.adelaide.edu.au Cc: cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-sys@FreeBSD.ORG, msmith@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/isa isa.c Message-ID: <199707281207.WAA15768@godzilla.zeta.org.au>
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>> Erm, it already used splhigh() to ensure this. > >Does splhigh() prevent fast interrupt handlers from being called? The No. >> Rule 1: No function can be called safely with CPU interrupts disabled. > >Can you explain "why" in simple terms? Because CPU interrupts should not be masked for long. Keeping calls short puts too much of a burden on the callee. Some caller (unknown to the callee) may be depending on the callee to take <= N usec. A minor algorithm change may invalidate this. Bruce
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