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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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
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