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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