Re: pte_pagenr/MAP_NR deleted in pre6

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> I'll probably be adding isa_virt_to_bus, because when it is in fact
> "ISA like" the driver already knows that it must be certain that the

isa_alloc_consistent makes sense actually. Its needed for ISA bus masters
on ancient mips and other crap

> physical address is below the 16MB mark right?  Then the cases left on

16Mb for ISA - except on a few late 486 era boxes with magic extensions (which
we'd finalyl be able to use)

> x86 are MCA (which can use the ISA interface) and PCI drivers which

no MCA bus is 32bit - its closer to PCI than ISA. mca_alloc_consistent is 
doable and if some loon ever does do old IBM power boxes it will be needed
as they apparently arent cache coherent MCA

> drivers.  For example, BTTV still doesn't use the PCI dma stuff simply
> because nobody wishes to use their brains a little bit and encapsulate
> the user DMA stuff into a common spot (it's duplicated in 4 or 5
> drivers) which uses scatter gather lists with the DMA api.

BTTV doesnt use it because the current stuff works and for post 2.4 using
mmap_kiovec() and similar stuff probably will be a better solution - that
will also help us to push PCI bug awareness into pci not drivers

Also mmap_kiovec will let i810 and some other sound cards do scatter gather
buffers sensibly.

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