Re: A simple question about readw, readw and the like

From: Jeff Garzik (jgarzik@mandrakesoft.com)
Date: Thu Jul 27 2000 - 11:51:47 EST


Abramo Bagnara wrote:
> Alan Cox wrote:
> > > Does this means that there is no way to mmap the PCI IO space on any
> > > platform other than ia32?

> > PCI mmap to user space can be done (obvious coherency and other issues left
> > to the user mode sufferer) but that isnt done by ioremap

> I suppose you mean I need to use remap_page_range with the address
> obtained from ioremap, don't you?

io_remap_page_range not remap_page_range. grep for it in the 2.4.x tree
to see example usage.

> But, that apart, is a device driver that give available a part of the
> PCI IO space of controlled card via mmap portable to all platforms that
> have PCI?

Assuming you have PCI shared memory space (MMIO) and not real PCI IO
space (PIO), and assuming you use io_remap_page_range, yes.

> And if this is true, the user application that use this mmaped area may
> be written in a platform independant way?

Your userland application must still get byteswapping and such correct.

        Jeff

-- 
Jeff Garzik              |
Building 1024            | Yossarian lives.
MandrakeSoft, Inc.       |

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