Date: Wed, 30 Dec 1998 00:58:06 +0900 From: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp> To: Mike Smith <mike@smith.net.au> Cc: current@FreeBSD.ORG, yokota@zodiac.mech.utsunomiya-u.ac.jp Subject: Re: future of syscons Message-ID: <199812291558.AAA16643@zodiac.mech.utsunomiya-u.ac.jp> In-Reply-To: Your message of "Mon, 28 Dec 1998 15:10:39 PST." <199812282310.PAA13485@dingo.cdrom.com> References: <199812282310.PAA13485@dingo.cdrom.com>
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>> It is true that IRQ 1 is always assigned to the keyboard controller on >> the AT motherboard and no device can claim it because IRQ 1 line is >> not available in expansion slots. >> >> The PS/2 mouse interrupt IRQ 12 is another story. IRQ 12 is available >> to ISA and PCI bus slots and you can assign it to a device! We >> shouldn't make the keyboard controller code to claim IRQ 12 when >> either 1) a PS/2 mouse is not detected, or 2) another device is using >> or going to use IRQ 12. > >Sure; by all means disable the interrupt handler if a ps/2 mouse is not >found, I think that "disabling the interrupt handler" is not enough, the IRQ 12 resource must be released and made available to other devices to claim. >but it's important to claim the interrupt in the keyboard >controller code if one *is* found, Yes. > or even just expected to be found (eg. attached after bootup). Well, as I wrote before, ISA cards can be set to use IRQ 12, or the PCI interrupt may be mapped to this IRQ. Therefore, when no PS/2 mouse is detected at boot time, it can safely claim the IRQ 12 only if the IRQ is not used by any other devices. # The PS/2 mouse port is generally not designed for "hot plugging". # Thus, in general it is very little use reserving the IRQ 12 if the mouse # is not detected at boot time; the mouse won't be connected later. Kazu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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