From: Matt Porter <porter@cox.net>
To: Brian Kuschak <bkuschak@yahoo.com>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: 4xx critical exceptions
Date: Wed, 4 Dec 2002 17:11:53 -0700 [thread overview]
Message-ID: <20021204171152.A11934@home.com> (raw)
In-Reply-To: <20021204230047.98430.qmail@web40912.mail.yahoo.com>; from bkuschak@yahoo.com on Wed, Dec 04, 2002 at 03:00:47PM -0800
On Wed, Dec 04, 2002 at 03:00:47PM -0800, Brian Kuschak wrote:
<snip>
> The COMMON_PROLOG in head_4xx.S uses SPRG0,1 to
> temporarily save r20, r21 for scratch use. Problem is
> this prologue is used for both critical and
> non-critical interrupts. As I understand it, MSR[EE]
> is cleared for external interrupts, but MSR[CE] is
> not. If a critical interrupt occurs while handling a
> non-critical interrupt, the SPRG0,1 can be overwritten
> while handling the critical interrupt.
>
> I'm guessing we don't have any unused SPRGx registers
> to use here. I was thinking about temporarily
> disabling CE until saving SPRG0,1, but that can't be
> done without using at least one register, and none of
> them are saved at that point.
>
> Any ideas?
The linuxppc-2.5 tree has a (partial) implementation of critical
exceptions. The method used is to save the registers into a
region preallocated in head_*.S.
> P.S. BTW, is bk://ppc.bkbits.net/linuxppc_2_5 the
> right place for the latest 2.5 code?
That's a dead tree. You want bk://ppc.bkbits.net/linuxppc-2.5
Regards,
--
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2002-12-05 0:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-04 23:00 4xx critical exceptions Brian Kuschak
2002-12-05 0:11 ` Matt Porter [this message]
2002-12-06 9:22 ` Kenneth Johansson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20021204171152.A11934@home.com \
--to=porter@cox.net \
--cc=bkuschak@yahoo.com \
--cc=linuxppc-embedded@lists.linuxppc.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).