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KernelTrap: Understanding The Stricter Type Checks

Sep 20, 2004, 04:00 (0 Talkback[s])

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"With the release of 2.6.9-rc2, Linus Torvalds mentioned the addition of stricter type checks for PCI memory mapping. He has since followed up with another email to explain these stricter type checks, 'this is a background mail mainly for driver writers and/or architecture people. Or others that are just interested in really low-level hw access details. Others--please feel free to ignore.' His lengthy background email was followed by some interesting discussion, offering further clarification. Linus begins:

"'The background for this iospace type-checking change is that we've long had some serious confusion about how to access PCI memory mapped IO (MMIO), mainly because on a PC (and some non-PC's too) that IO really does look like regular memory, so you can have a driver that just accesses a pointer directly, and it will actually work on most machines...'"

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