linux-kernel - Re: pci_fixup_video change blows up on sparc64

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Message-ID: <20061020040324.GA8014@kroah.com>
Date:	Thu, 19 Oct 2006 21:03:24 -0700
From:	Greg KH <greg@...ah.com>
To:	eiichiro.oiwa.nm@...achi.com
Cc:	David Miller <davem@...emloft.net>, alan@...hat.com,
	jesse.barnes@...el.com, linux-kernel@...r.kernel.org
Subject: Re: pci_fixup_video change blows up on sparc64

On Fri, Oct 20, 2006 at 12:21:24PM +0900, eiichiro.oiwa.nm@...achi.com wrote:
> From: Greg KH <greg@...ah.com>
> >On Thu, Oct 19, 2006 at 03:32:28PM -0700, David Miller wrote:
> >> From: <eiichiro.oiwa.nm@...achi.com>
> >> Date: Thu, 19 Oct 2006 19:49:26 +0900
> >> 
> >> > The "0xc0000" is a physical address. The BAR (PCI base address) is also
> >> > a physcail address. There are no difference.
> >> 
> >> Your assertion that the BAR is a physical address is very platform
> >> specific.  It may be a "physical address in PCI bus space", but
> >> that has no relation to the first argument passed to ioremap()
> >> which is defined in a completely different way.
> >> 
> >> On many platforms, the BAR of PCI devices are translated into an
> >> appropriate "ioremap() cookie" in the struct pci_dev resource[] array
> >> entries, so that they can be used properly as the first argument to
> >> ioremap().  Only address cookies properly setup by the platform may be
> >> legally passed into ioremap() as the first argument.  No such setups
> >> are being made on this raw 0xc0000 address.
> >> 
> >> So, as you can see, I/O port and I/O memory space work differently on
> >> different platforms and this abstraction of the first argument to
> >> ioremap() is how we provide support for such differences.
> >> 
> >> If you try to access 0xc0000 via ioremap() on sparc64, it is going to
> >> try and access that area non-cacheable which, since 0xc0000 is
> >> physical RAM, will result in a BUS ERROR and a crash.
> >> 
> >> This physical location might be the area for the video ROM on x86,
> >> x86_64, and perhaps even IA64, but it certainly is not used this way
> >> on sparc64 systems.
> >> 
> >> I really would like to see this regression fixed, or at the very
> >> least this code protected by X86, X86_64, IA64 conditionals.
> >
> >I agree.  Eiichiro, care to send me an patch to fix this somehow?  Or do
> >you want me to just revert it?
> >
> >thanks,
> >
> >greg k-h
> >
> 
> Ok, I sent an patch to fix on only x86, x86_64 and IA64 for 2.6.18.
> Do you need an patch aganist 2.6.19-git?

I can't apply a patch against an old kernel, especially when the problem
is with the new release :)

Please make it against Linus's latest tree, which is where the problem
is.  Also, please address David's latest comments about the patch.

thanks,

greg k-h
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