From: Gary Thomas <gary@mlbassoc.com>
To: Brian Waite <waite@skycomputers.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linuxppc-dev <linuxppc-dev@lists.linuxppc.org>
Subject: Re: Disable cache on 74xx
Date: 20 Feb 2003 07:01:39 -0700 [thread overview]
Message-ID: <1045749699.18487.7532.camel@hermes.chez-thomas.org> (raw)
In-Reply-To: <200302200855.12224.waite@skycomputers.com>
On Thu, 2003-02-20 at 06:55, Brian Waite wrote:
> According to The User's Manual, the data cache instructions become no-ops if
> the data cache is disabled.
>
There are "User Manuals" and then there is "Real Life". My
experience has been that trying to execute these instructions
with the cache disabled was treated like an invalid instruction
(hence causing a trap). Maybe this isn't always true with all
PowerPC processors, but I was just pointing out that you might
run into trouble with it.
> Thanks
> Brian
> On Wednesday 19 February 2003 5:48 pm, Gary Thomas wrote:
> > On Wed, 2003-02-19 at 14:07, Benjamin Herrenschmidt wrote:
> > > On Wed, 2003-02-19 at 21:52, Brian Waite wrote:
> > > > Hi all,
> > > > I am trying to hunt down a memory controller configuration problem and
> > > > I have been asked to disable all caching so as to remove it from the
> > > > equation. I can easl disable L2 but when I start ucking with the WIMG
> > > > bits to set cache inhibit, The kernel panics with stack overflows. Does
> > > > anyone know where or what I have to set to disable caching?
> > >
> > > Hrm... set L2 and L3 off, then hack HID0 to disable L1 ?
> >
> > There are other problems with this. With the caches disabled
> > (via HID0) all data cache instructions (like DCBF) will fail.
> > There are some of these in the kernel itself, but beware that
> > GLIBC has it's own set.
> >
> > ... totally disabling the data CACHE with Linux is non-trivial.
--
------------------------------------------------------------
Gary Thomas |
MLB Associates | Consulting for the
+1 (970) 229-1963 | Embedded world
http://www.mlbassoc.com/ |
email: <gary@mlbassoc.com> |
gpg: http://www.chez-thomas.org/gary/gpg_key.asc
------------------------------------------------------------
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2003-02-20 14:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-19 20:52 Disable cache on 74xx Brian Waite
2003-02-19 21:07 ` Benjamin Herrenschmidt
2003-02-19 22:48 ` Gary Thomas
2003-02-20 13:55 ` Brian Waite
2003-02-20 14:01 ` Gary Thomas [this message]
2003-02-20 14:09 ` Geert Uytterhoeven
2003-02-20 15:23 ` Dan Malek
2003-02-20 15:47 ` Brian Waite
2003-02-20 15:54 ` Gary Thomas
2003-02-20 15:55 ` Benjamin Herrenschmidt
2003-02-20 16:14 ` Dan Malek
2003-02-20 16:51 ` Mark A. Greer
2003-02-20 14:09 ` Brian Waite
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=1045749699.18487.7532.camel@hermes.chez-thomas.org \
--to=gary@mlbassoc.com \
--cc=benh@kernel.crashing.org \
--cc=linuxppc-dev@lists.linuxppc.org \
--cc=waite@skycomputers.com \
/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).