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.f02K6VG01723@meow.osd.bsdi.com>
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Part III...
-----FW: Re: PC164 IDE only works (was: SMPng stability)-----
Date: Fri, 17 Nov 2000 10:51:31 -0800 (PST)
From: John Baldwin <jhb@FreeBSD.org>
To: Andrew Gallatin <gallatin@cs.duke.edu>
Subject: Re: PC164 IDE only works (was: SMPng stability)
Cc: mjacob@feral.com
On 17-Nov-00 Andrew Gallatin wrote:
>
> Next question -- how the heck do we keep the ipl at ALPHA_PSL_IPL_IO
> until the interrupt thread is run? Can you muck with the psl in the
> in hardware frame and have the palcode beleive you?
>
> Keeping the ipl at 4 will also mean mucking with exception return,
> etc, etc, etc. Ick.
Well, first of all, we should only do this for PC164's as this is going to kill
interrupt performance. :( You can muck with the IPL in the saved psr on the
stack. You will only need to do this for DEVICE_IO interrupts. And you can do
it by writing the current IPL into the saved frame from within interrupt().
IOW, in the DEVICE_IO case block, have something like:
if (user_has_a_lame_pc164) {
frame.psr &= ~ALPHA_PSR_IPL_MASK;
frame.psr |= alpha_read_psr() & ALPHA_PSR_IPL_MASK;
}
Then in ithd_loop(), before grabbing sched_lock via mtx_enter(), add in:
if (user_has_a_lame_pc164)
alpha_pal_swpipl(ALPHA_PSL_IPL_0);
That should do the trick.
> 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/
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