From: Segher Boessenkool <segher@kernel.crashing.org>
To: olof@lixom.net (Olof Johansson)
Cc: linuxppc-dev@ozlabs.org, paulus@samba.org
Subject: Re: [PATCH] DMA 4GB boundary protection
Date: Sun, 4 Mar 2007 00:32:04 +0100 [thread overview]
Message-ID: <8049bab22e1c006dcf916eb12202b73d@kernel.crashing.org> (raw)
In-Reply-To: <20070303232915.GB8028@lixom.net>
> The drawback of this patch is that it adds code to every single
> allocation.
> Instead, you should just mark the last entry before the 4GB boundary
> as allocated when you setup the bitmaps for the table. That way, no
> allocation will ever be able to cross over.
Jake said that this bug happens when crossing _any_ 4GB
boundary, so that means reserving a few more blocks.
> Even nicer would be to only do it when a boot option is specified, so
> we actually have a chance to expose and find the driver bugs instead of
> papering them over.
Almost all drivers (*) that can do DAC already avoid
crossing the SAC-to-DAC boundary. I have never heard
about a card having the bug on _any_ 4GB crossing, I
doubt they are that common. Just fix the drivers :-)
(*) Well, amongst those that matter and have this bug.
Segher
next prev parent reply other threads:[~2007-03-03 23:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-02 21:49 [PATCH] DMA 4GB boundary protection Jake Moilanen
2007-03-02 22:27 ` Olof Johansson
2007-03-03 8:27 ` Benjamin Herrenschmidt
2007-03-03 23:25 ` Olof Johansson
2007-03-04 5:17 ` Christoph Hellwig
2007-03-04 5:52 ` Olof Johansson
2007-03-03 23:29 ` Olof Johansson
2007-03-03 23:32 ` Segher Boessenkool [this message]
2007-03-03 23:57 ` Olof Johansson
2007-03-21 21:05 ` Jake Moilanen
2007-03-21 21:39 ` Olof Johansson
2007-03-22 17:53 ` Olof Johansson
2007-03-22 17:47 ` Jake Moilanen
2007-03-22 22:52 ` Segher Boessenkool
2007-03-27 20:10 ` Jake Moilanen
2007-03-27 20:55 ` Benjamin Herrenschmidt
2007-03-27 23:48 ` Paul Mackerras
2007-03-28 15:56 ` Olof Johansson
2007-03-28 18:17 ` Jake Moilanen
2007-03-28 23:23 ` Benjamin Herrenschmidt
2007-03-29 13:44 ` Jake Moilanen
2007-03-29 14:52 ` Olof Johansson
2007-03-29 21:54 ` Benjamin Herrenschmidt
2007-04-23 12:22 ` Paul Mackerras
2007-04-24 3:07 ` Olof 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=8049bab22e1c006dcf916eb12202b73d@kernel.crashing.org \
--to=segher@kernel.crashing.org \
--cc=linuxppc-dev@ozlabs.org \
--cc=olof@lixom.net \
--cc=paulus@samba.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.