Mmaping vmallocated memory to user space

From: Martin Frey (frey@scs.ch)
Date: Sat Jun 10 2000 - 16:23:05 EDT

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    Dear all,

    I need to mmap vmallocated memory from a device driver to user
    space. I implemented to vm_nopage method as described in the
    Rubini book.
    But at the address returned by the mmap call I see a different
    memory location than in the driver. The memory is the same
    as when I mmap /dev/mem for the same offset as the physical
    address of my driver allocated buffer.
    I also tried to call remap_page_range directly in the mmap
    kernel interface (as e.g. /dev/mem does), but I get the same
    result.
    I'm using 2.2.14 on a DS20 Alpha box.

    My address returned by vmalloc is 0xfffffe0000048000,
    the physical address feeded to remap_page_range is
    0x48000 (virt_to_phys returns that).
    Scanning the whole 1st GB of memory mapped over /dev/mem
    does not show the data patterns I stored in the
    vmallocated area.

    Can anybody help?

    Thanks and best regards,

    Martin Frey 

    -- 
Supercomputing Systems AG        email: frey@scs.ch	
Martin Frey                      www:   http://www.scs.ch/~frey
Technoparkstrasse 1		 phone: +41 (0)1 445 16 00
CH-8005 Zurich			 fax:	+41 (0)1 445 16 10

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