Date: Fri, 31 May 2002 10:01:11 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Bosko Milekic <bmilekic@unixdaemons.com> Cc: freebsd-smp@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG, Aaro J Koskinen <akoskine@cc.helsinki.fi> Subject: Re: ICU_LEN with IO APIC Message-ID: <XFMail.20020531100111.jhb@FreeBSD.org> In-Reply-To: <20020531092348.B69469@unixdaemons.com>
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On 31-May-2002 Bosko Milekic wrote: > > On Fri, May 31, 2002 at 12:12:00PM +0300, Aaro J Koskinen wrote: >> Hello, >> >> Is there any particular reason why the number of interrupts is limited >> to 32 on APIC systems? Is it just a conservative guess on the number of >> interrupts anyone might want to need...? > > I'm not sure but perhaps this is historical (and now also required > again), but if we use a word to mask out interrupts than after 32 we > run out of bits. "Who needs more than 32 interrupts anyway?!" :-) Actually, the historical value in stable is 24 because the same 32-bit word shares the 8 softinterrupts with 24 hardware interrupts. I think the APIC only has 32 interrupt pins however. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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