Date: Tue, 02 Jan 2001 12:06:56 -0800 (PST) From: John Baldwin <john@baldwin.cx> To: alpha@FreeBSD.org Subject: Disabling ints via IPL Message-ID: <XFMail.010102120656.john@baldwin.cx> Resent-Message-ID: <200101022006.f02K6WG01735@meow.osd.bsdi.com>
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Part VI: On 17-Nov-00 Andrew Gallatin wrote: > So the answer is "yes; but its not as bad I thought" because the > ithread is going to run fairly soon. > > It would seem that we don't need to go messing with the frame. All we > really need to do is to avoid dropping the IPL prior to running the > AST if we're on a PC164. And also never mask any interrupts if we're > on a PC164, since it seems the real problem is with unmasking them. We still have to mess with the frame to handle the case when we get an interrupt while we are in teh kernel and we don't call ast() on the way out. > It would also seem that we need to make sure we have enough room on > the kernel stack to store "recursive" interrupt contexts for each > platform, one frame for each irq that could possibly come in when we > drop the IPL to 0 in exception_return(). It won't be dropped to 0 unless a non-device I/O interrupt posts an ast and is returning to userland. > Drew -- John Baldwin <john@baldwin.cx> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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