From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Dan Malek <dan@embeddedalley.com>
Cc: debian-powerpc@lists.debian.org, linuxppc-dev@ozlabs.org
Subject: Re: Unmapping pages from the linear addressing without HIGHMEM support
Date: Sat, 11 Mar 2006 10:12:31 +1100 [thread overview]
Message-ID: <1142032351.4057.29.camel@localhost.localdomain> (raw)
In-Reply-To: <051c9d8f422b0e5289b7083367cf44ca@embeddedalley.com>
On Fri, 2006-03-10 at 07:59 -0500, Dan Malek wrote:
> On Mar 10, 2006, at 4:09 AM, Gerhard Pircher wrote:
>
> > That would mean I cannot reuse the code in dma-mapping.c, right?
>
> Sure you can. All you need to do is turn of BAT mapping, which
> is as easy as using the 'nobats' command line parameter and
> all of this code should just work for you.
And the kernel will blow up in flames under various funny circumstances
and you'll lose a fair amount of performances.
The 6xx kernel requires at least the IBAT mapping the kernel text. Some
of the exception handling code path can't deal with getting a hash fault
at critical locations (they can mostly deal with data hash misses
nowadays, but the code has to be accessible at all times).
> > ... but I guess I have to setup my own page table for the reserved
> > DMA memory area and implement my own alloc_pages() function!?
>
> No, that's already done for you behind all of these functions.
>
> Thanks.
>
> -- Dan
>
>
next prev parent reply other threads:[~2006-03-10 23:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-09 13:51 Unmapping pages from the linear addressing without HIGHMEM support Gerhard Pircher
2006-03-09 22:11 ` Benjamin Herrenschmidt
2006-03-10 9:09 ` Gerhard Pircher
2006-03-10 12:59 ` Dan Malek
2006-03-10 23:12 ` Benjamin Herrenschmidt [this message]
2006-03-10 23:13 ` Benjamin Herrenschmidt
2006-03-11 13:28 ` Gerhard Pircher
2006-03-12 0:07 ` Benjamin Herrenschmidt
[not found] <31042.1141997321@www088.gmx.net>
2006-03-10 13:31 ` Gerhard Pircher
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