Messages in this thread | | | Date | Wed, 21 Nov 2001 00:02:30 -0500 | From | Douglas Gilbert <> | Subject | mmap-ing __get_free_pages(), order > 0 |
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I'm trying to mmap a scatter gather list to the user space. [The scatter gather list has the same lifetime as a file descriptor to a device.] Each element of the scatter gather list is obtained from __get_free_pages() [typically order == 3].
In LDD2, Rubini & Corbett limit their "scullp" driver example to order 0. There is a bit of arm waving in the text (page 392) about some manipulation of page counts being required when the order is > 0.
Could someone please elaborate what the rules are (for the "nopage" callback)? [The DEBUG_LRU_PAGE() at line 206 of page_alloc.c disapproves of my attempts to date.]
Is there any driver out there that solves this particular problem?
Doug Gilbert
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