From: "Mark A. Greer" <mgreer@mvista•com>
To: Dan Malek <dan@embeddededge•com>
Cc: linuxppc-dev@ozlabs•org, John Reiser <jreiser@BitWagon•com>
Subject: Re: 2GB address space limit on 32-bit PowerPC Macintosh
Date: Mon, 16 May 2005 13:43:36 -0700 [thread overview]
Message-ID: <428905F8.4030204@mvista.com> (raw)
In-Reply-To: <2dd506f0a6d4b03e771c0bc9d80735e6@embeddededge.com>
Dan Malek wrote:
>
> On May 16, 2005, at 2:06 PM, Mark A. Greer wrote:
>
>> Oops...
>> /me unintentionally stepped into the middle of a flame war :)
>
>
> Just pee on it :-)
Heh!
>
>
>> To be clear, "offender" == board that has an io_block_mapping below
>> the 3 GB line.
>
>
> That is one of the obvious changes. You are likely to find some other
> assumptions
> that may need attention. The problem with io_block_mapping is you
> just can't
> remove it, you have to fix up all of the code that is based on the
> assumption these
> spaces are mapped. You are likely to find yourself in a situation
> where you need
> access to some board control registers before VM is set up and you can
> call
> ioremap(). So, you will find yourself doing some hack in head.S to
> map BAT
> registers to get access to this, which is exactly what
> io_block_mapping() does,
> only in a way that is obvious :-)
I think I understand all of that. I wasn't clear in my email. I was
talking about "fixing" such that 3GB works (i.e., io_block_mapping are
above 3GB virt, if possible) not "fixing" such that we can get rid of
io_block_mapping altogether. We still need io_block_mapping for exactly
the reasons you state.
I need to learn how to write better emails... :(
Mark
next prev parent reply other threads:[~2005-05-16 20:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-15 22:36 2GB address space limit on 32-bit PowerPC Macintosh John Reiser
2005-05-15 23:01 ` Benjamin Herrenschmidt
2005-05-15 23:29 ` Paul Mackerras
2005-05-15 23:34 ` Benjamin Herrenschmidt
2005-05-16 5:51 ` Kumar Gala
2005-05-16 5:52 ` Benjamin Herrenschmidt
2005-05-16 6:21 ` Kumar Gala
2005-05-16 6:22 ` Benjamin Herrenschmidt
2005-05-16 15:04 ` Dan Malek
2005-05-16 15:05 ` Benjamin Herrenschmidt
2005-05-16 15:52 ` Dan Malek
2005-05-16 16:42 ` Benjamin Herrenschmidt
2005-05-16 17:11 ` Dan Malek
2005-05-17 0:54 ` Benjamin Herrenschmidt
2005-05-16 18:00 ` Mark A. Greer
2005-05-16 18:06 ` Mark A. Greer
2005-05-16 20:31 ` Dan Malek
2005-05-16 20:43 ` Mark A. Greer [this message]
2005-05-16 21:02 ` Dan Malek
2005-05-17 3:14 ` Benjamin Herrenschmidt
2005-05-17 0:56 ` Benjamin Herrenschmidt
2005-05-16 16:11 ` Wolfgang Denk
2005-05-16 16:22 ` Eugene Surovegin
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