Subject: Re: USB controller goes nuts on Alpha
To: Nathan J. Williams <nathanw@MIT.EDU>
From: Chris G. Demetriou <firstname.lastname@example.org>
Date: 02/08/2000 12:28:20
nathanw@MIT.EDU (Nathan J. Williams) writes:
> On the Alpha, device interrupts can come in at IPL 3 or
> 4; the spl calls that block device interrupts set the IPL to 4. The
> ohci interrupt happened to come in at 3, so _s got the value 3 and _su
> got 4, even though further ohci interrupts would be blocked.
OK, so, this points to a bogon in the alpha interrupt code.
If the device interrupts can come in at either 3 or 4 (with the kernel
not easily determining which beforehand), then it's the interrupt
handler's responsibility to block all both 4 and 3.
i.e. by the time the handler is called, 4 should already be blocked.
Chris Demetriou - email@example.com - http://www.netbsd.org/People/Pages/cgd.html
Disclaimer: Not speaking for NetBSD, just expressing my own opinion.