Messages in this thread | | | From | (Alan Cox) | Subject | Re: user space writel() etc. in 2.2.2 | Date | Fri, 5 Mar 1999 19:34:42 +0000 (GMT) |
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> Besides, why i386/io.h does not know anything about writel() in non > __KERNEL__ , whereas alpha/io.h declares them as extern. That sure is > inconsitent.
Because its non portable.
> On the other hand - WHY one loses portability doing IO memory access on > different architectures? Sure enough that PCI memory would be present on > any architecture that has that PCI plugged in, and registers would be the > same (though ordering might differ, and that is the responsibility of > writel() etc. to handle it.
Does the bus reverse the bytes in the long words, does it do PCI posting, how is I/O space mapped - memory, I/O instructions, are different size or endian mappings present at different offsets.
Then you can add write posting, cache coherency and the like.
Alan
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