Date: Fri, 17 Nov 2000 22:18:50 +0100 (CET) From: =?ISO-8859-1?Q?G=E9rard_Roudier?= <groudier@club-internet.fr> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: Bernd Walter <ticso@cicely8.cicely.de>, 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: <Pine.LNX.4.10.10011172209490.1542-100000@linux.local> In-Reply-To: <14869.25705.810908.875060@grasshopper.cs.duke.edu>
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On Fri, 17 Nov 2000, Andrew Gallatin wrote: >=20 > An interesting comment found in the linux kernel sources: >=20 > /* In theory, the PC164 has the same interrupt hardware as > the other Cabriolet based systems. However, something=20 > got screwed up late in the development cycle which broke > the interrupt masking hardware. Repeat, it is not=20 > possible to mask and ack interrupts. At all. >=20 > In an attempt to work around this, while processing=20 > interrupts, we do not allow the IPL to drop below what > it is currently. This prevents the possibility of > recursion. =20 >=20 > ??? Another option might be to force all PCI devices > to use edge triggered rather than level triggered > interrupts. That might be too invasive though. */ >=20 >=20 > Drew Interesting, indeed. Note that using edge triggerred interrupt for PCI devices is a broken idea, since it would just break numerous drivers by making them lose interrupt conditions. Btw, in my opinion, handling level sensitive interrupts from some scheduled entity (i.e. not in the corresponding interrupt context) does not look a better idea to me for other reasons. This let me consider the above hardware not to be broken given proper handling of level sensitive interrupts. G=E9rard. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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