RE: Specifying properly the PCI driver model on all linux archite

Bret Indrelee (bindrelee@sbs-cp.com)
Tue, 2 Nov 1999 12:56:36 -0600

Jakub Jelinek [mailto:jakub@redhat.com] wrote:
> The address returned by ioremap is not a virtual address, it
> is a cookie
> which readb/w/l etc. take as arguments.
> E.g. on sparc64, ioremap returns you the physical address
> (ie. ioremap just
> returns first argument and does nothing else) and readb and
> the like use
> instructions to bypass caches which take that physical
> address (so that it
> does not use any TLB entries).

Doesn't this break mmap() on SPARC?

I thought it was a kernel address, and thus you could use it to memory map
device addresses into user address space. I haven't yet gotten to that part
of the driver, so I'm not familiar (yet) with Linux mmap() entry point.

I do know that there is no hardware reason on SPARC where this wouldn't be
possible. We do Solaris drivers, and provide a capability to mmap() in parts
of the device address space.

-Bret

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