Re: Question about ioremap and io_remap_page_range

[Jonathan Lundell]

At 8:33 AM -0600 2001-09-27, Jonathan Corbet wrote:
>  > >      VIRT_ADDR = ioremap(BUS_ADDR); to map a section of PCI memory, and
>>  >      X_ADDR = virt_to_phys(VIRT_ADDR);
>>
>>  i'd suggest to read Documentation/DMA-mapping.txt in any recent kernel
>>  source, the bus_to_virt()/virt_to_phys() interface is obsolete and has
>>  been replaced by the pci_alloc_*/pci_map_*/pci_free_*() dynamic
>>  DMA-mapping API.
>
>...or, of course, _Linux_Device_Drivers_, Second Edition, available online
>at http://www.xml.com/ldd/chapter/book/index.html.  The DMA chapter covers
>this API as well.

That chapter says, in small part,

>Based on this discussion, you might also want to map addresses 
>returned by ioremap to user space. This mapping is easily 
>accomplished because you can use remap_page_range directly, without 
>implementing methods for virtual memory areas. In other words, 
>remap_page_range is already usable for building new page tables that 
>map I/O memory to user space

Are you suggesting that ioremap() objects can be passed to 
remap_page_range()? How can that be valid?

Also, there's an html conversion error:

>      if (offset >= _ _pa(high_memory) || (filp->f_flags & O_SYNC))

  Looks like   got translated to  
-- 
/Jonathan Lundell.