Re: pci_fixup_video change blows up on sparc64

[<eiichiro.oiwa.nm@hitachi.com>]

From: Greg KH <greg@kroah.com>
>On Fri, Oct 20, 2006 at 12:21:24PM +0900, eiichiro.oiwa.nm@hitachi.com wrote:
>> From: Greg KH <greg@kroah.com>
>> >On Thu, Oct 19, 2006 at 03:32:28PM -0700, David Miller wrote:
>> >> From: <eiichiro.oiwa.nm@hitachi.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
Ok, I understood. Thank you a lot.

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