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Subjectmmap not working?


I want to mmap a device in an application, so I do:

base = mmap(NULL , DEV_LENGTH, myprot , flags, kmem, dev_base);

Turns out that some BIOSs put my device at an address like


whereas others put it at 0xfa000000 . In the latter case, mmap works
as expected. However in the first case I get EINVAL: The base is
not page-aligned.

However, in the latter case I get my requested 1k of memory, and the
following 3k for free. In the first case I'd want "3k for free,
followed by the 1k I requested".

effectively, provided "start" equals NULL, the kernel IMHO should:

offset = dev_base & PAGE_MASK;
return mmap (NULL, length+offset, prot, flags, base - offset) + offset;

The "failure" was observed on 2.4.14 and/or 2.4.9.


P.S. I end up not being able to closely follow linux-kernel
lately. CCs to me appreciated.

** ** ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
* There are old pilots, and there are bold pilots.
* There are also old, bald pilots.
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