Date: Fri, 17 Nov 2000 12:05:47 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Bernd Walter <ticso@cicely8.cicely.de> Cc: John Baldwin <jhb@FreeBSD.org>, Christian Weisgerber <naddy@mips.inka.de>, freebsd-alpha@FreeBSD.org Subject: Re: PC164 IDE only works (was: SMPng stability) Message-ID: <14869.25705.810908.875060@grasshopper.cs.duke.edu> In-Reply-To: <20001116221125.A12204@cicely8.cicely.de> References: <20001116212040.A12094@cicely8.cicely.de> <XFMail.001116125448.jhb@FreeBSD.org> <20001116221125.A12204@cicely8.cicely.de>
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An interesting comment found in the linux kernel sources:
/* In theory, the PC164 has the same interrupt hardware as
the other Cabriolet based systems. However, something
got screwed up late in the development cycle which broke
the interrupt masking hardware. Repeat, it is not
possible to mask and ack interrupts. At all.
In an attempt to work around this, while processing
interrupts, we do not allow the IPL to drop below what
it is currently. This prevents the possibility of
recursion.
??? Another option might be to force all PCI devices
to use edge triggered rather than level triggered
interrupts. That might be too invasive though. */
Drew
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