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Re: IP22 64bit kernel

To: Kumba <kumba@gentoo.org>
Subject: Re: IP22 64bit kernel
From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 13 Sep 2007 16:50:59 +0100
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>, linux-mips@linux-mips.org
In-reply-to: <46E8E134.8000004@gentoo.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070911213048.GA20579@alpha.franken.de> <46E8E134.8000004@gentoo.org>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.14 (2007-02-12)
On Thu, Sep 13, 2007 at 03:05:24AM -0400, Kumba wrote:

> >Enabling this for (CONFIG_SGI_IP22 && CONFIG_64BIT) fixes the boot problem.
> >It's not big deal to add this, but I'm wondering why we not just always
> >use this macro ? What platforms do it break with it ?
> 
> Hmm, curious, the CONFIG_ARC64 macro?  Indys and O2s use 32bit versions of 
> the ARCS Prom, whereas Octane, Origin, and IP28 systems (and others) use 
> 64bit.  I suspect CONFIG_ARC64 is geared for these, but if it works on 
> Indy's too, that's curious.

The problem isn't limited to ARC firmware; basically any non-R8000 64-bit
system can be affected.  A kernel may be using either addresses in XKPHYS
or in CKSEG0 and the segment for which the kernel is linked is not
necessarily the same that the firmware will load it to.

  Ralf

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