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| author | Kai Jiang <Kai.Jiang@freescale.com> | 2011-10-17 20:50:20 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-18 11:18:57 -0700 |
| commit | 27a90700a4275c5178b883b65927affdafa5185c (patch) | |
| tree | d140a0c39bc0bf68531a165e0678be58987d2d78 /Documentation/DocBook | |
| parent | c4253cb0748cd50060d04d838c38b07f1ad0e6e5 (diff) | |
| download | linux-27a90700a4275c5178b883b65927affdafa5185c.tar.gz | |
uio: Support physical addresses >32 bits on 32-bit systems
To support >32-bit physical addresses for UIO_MEM_PHYS type we need to
extend the width of 'addr' in struct uio_mem. Numerous platforms like
embedded PPC, ARM, and X86 have support for systems with larger physical
address than logical.
Since 'addr' may contain a physical, logical, or virtual address the
easiest solution is to just change the type to 'phys_addr_t' which
should always be greater than or equal to the sizeof(void *) such that
it can properly hold any of the address types.
For physical address we can support up to a 44-bit physical address on a
typical 32-bit system as we utilize remap_pfn_range() for the mapping of
the memory region and pfn's are represnted by shifting the address by
the page size (typically 4k).
Signed-off-by: Kai Jiang <Kai.Jiang@freescale.com>
Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Hans J. Koch <hjk@hansjkoch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/uio-howto.tmpl | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl index 7c4b514d62b1..54883de5d5f9 100644 --- a/Documentation/DocBook/uio-howto.tmpl +++ b/Documentation/DocBook/uio-howto.tmpl @@ -529,7 +529,7 @@ memory (e.g. allocated with <function>kmalloc()</function>). There's also </para></listitem> <listitem><para> -<varname>unsigned long addr</varname>: Required if the mapping is used. +<varname>phys_addr_t addr</varname>: Required if the mapping is used. Fill in the address of your memory block. This address is the one that appears in sysfs. </para></listitem> |