Messages in this thread | | | From | Kumar Gala <> | Subject | Re: [PATCH 6/13] devres: implement managed iomap interface | Date | Thu, 10 Apr 2008 14:40:52 -0500 |
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On Apr 10, 2008, at 1:24 PM, Sergei Shtylyov wrote: > Kumar Gala wrote: > >>>>>> Those functions are going to break on 32-bit platforms with >>>>>> extended physical address (well, that's starting with Pentiums >>>>>> which had 36-bit PAE :-) AND devices mapped beyond 4 GB (e.g. >>>>>> PowerPC 44x). You should have used resource_size_t for the >>>>>> 'offset' parameter. As this most probably means that libata is >>>>>> broken on such platforms, I'm going to submit a patch... > >>>> It's broken with drivers using MMIO, I meant to say. > >>> Oops, I meant PCI drivers here, at least for the time being. And >>> it looks like that was a false alarm. :-] > >>>>> Yeah, right please go ahead. But I wonder whether any BIOS was >>>>> actually crazy enough to map mmio region above 4G on 32bit >>>>> machine. > >>>> This is a *hardware* mapping on some non-x86 platforms (like >>>> PPC 44x or MIPS Alchemy). The arch/ppc/ and arch/mips/ kernels >>>> have special hooks called from ioremap() which help create an >>>> illusion that the PCI memory space on such platforms (not only >>>> it) is mapped below 4 GB; arch/powerpc/ kernel doesn't do this >>>> anymore -- hence this newly encountered issue. > >>> I thought that pcim_iomap() used devm_ioremap() or something -- >>> which of course turned to be wrong. devm_ioremap() alone is yet >>> safe since there are no users for it amongst PPC 44x platform >>> device drivers... > >> but there is no reason not to make it work properly. For example >> I believe libata uses devm_* and the fsl SATA driver (non-PCI) >> will need to work in cases similar to the 44x. > > Well, as for sata_fsl, it calls of_iomap() which does The Right > Thing.
Fair, but I don't see why we should introduce new APIs that are already "broken". We went through a lot of effort to clean up and introduce resource_t (and clearly still have some bugs) for the >32- bit physical address problem.
- k
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