Re: kernel VM area issue

[Christoph Hellwig <hch@ns.caldera.de>]

On Tue, Oct 02, 2001 at 04:40:28PM +0200, Martin Maletinsky wrote:
> 1) They may be within the start region of kernel virtual addresses (the addresses between PAGE_OFFSET and PAGE_OFFSET + size of physical memory). This region provides a 1:1
> mapping between physikal and (kernel) virtual addresses, phys_to_virt() and virt_to_phys() provide conversion between (kernel) virtual addresses from this region and
> physikal addresses.

Note that virt_to_phys/phys_to_virt are a 2.2-legacy interface.
As Linux 2.4 has a mm that is fundamentally page-based due to the highmem
support you did not claim to understand above, virt_to_page/page_address
are the preffered interface.

For a page that actually is highmem use kmap(page) instead and unmap it
with kunmap(page) again.

Both give you a kernel-virtual and not a physical address.
For lowmem pages __pa(addr) gives the real physical address.

	Christoph

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