Re: Question about ioremap and io_remap_page_range

Russell King (rmk@arm.linux.org.uk)
Thu, 27 Sep 2001 09:16:01 +0100

On Thu, Sep 27, 2001 at 10:03:26AM +0200, Armin Schindler wrote:
> virt_to_phys() is obsolete ? What should be used if I need the phys address
> of a memory page ? (e.g. for mmap() remapping)

virt_to_phys is only valid on the kernel direct mapped RAM area - memory
returned from kmalloc and non-highmem memory returned from get_free_page.

Since vmalloc and ioremap do not return a pointer into the direct mapped
RAM area, but its own mapping, it is not valid to use virt_to_phys on
these returned values, even through it might be a virtual address.

--
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html


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