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SubjectRe: [PATCH 6/13] devres: implement managed iomap interface
Tejun Heo wrote:

>> A very late comment but nevertheless... :-)

> Better late than never.

:-)

>> 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.

> 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.

WBR, Sergei


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