Lines Matching refs:of

16  (*) Cost of temporary mappings.
25 High memory (highmem) is used when the size of physical memory approaches or
26 exceeds the maximum size of virtual memory.  At that point it becomes
27 impossible for the kernel to keep all of the available physical memory mapped
28 at all times.  This means the kernel needs to start using temporary mappings of
29 the pieces of physical memory that it wants to access.
31 The part of (physical) memory not covered by a permanent mapping is what we
51 This means that the kernel can at most map 1GiB of physical memory at any one
53 temporary maps to access the rest of the physical memory - the actual direct
65 The kernel contains several ways of creating temporary mappings:
67  (*) vmap().  This can be used to make a long duration mapping of multiple
71  (*) kmap().  This permits a short duration mapping of a single page.  It needs
76  (*) kmap_atomic().  This permits a very short duration mapping of a single
92 wants to access the contents of a page that might be allocated from high memory
96 	/* Find the page of interest. */
99 	/* Gain access to the contents of that page. */
102 	/* Do something to the contents of that page. */
108 Note that the kunmap_atomic() call takes the result of the kmap_atomic() call
127 The cost of creating temporary mappings can be quite high.  The arch has to
131 simply with a bit of arithmetic that will convert the page struct address into
144 of RAM into your 32-bit machine.  This has a number of consequences:
150      page being 32-bytes that would end up being something in the order of 112G
151      worth of pages; the kernel, however, needs to store more than just