patch-2.3.46 linux/Documentation/DMA-mapping.txt

• Lines: 18
• Date: Mon Feb 14 15:31:14 2000
• Orig file: v2.3.45/linux/Documentation/DMA-mapping.txt
• Orig date: Fri Jan 28 15:09:06 2000

diff -u --recursive --new-file v2.3.45/linux/Documentation/DMA-mapping.txt linux/Documentation/DMA-mapping.txt
@@ -55,9 +55,15 @@
 __get_free_pages (but takes size instead of page order).
 It returns two values: the virtual address which you can use to access it
 from the CPU and dma_handle which you pass to the card.
-The return address is guaranteed to be page aligned.
 
-To unmap and free such DMA region, you call:
+The cpu return address and the DMA bus master address are both
+guaranteed to be aligned to the smallest PAGE_SIZE order which
+is greater than or equal to the requested size.  This invariant
+exists (for example) to guarentee that if you allocate a chunk
+which is smaller than or equal to 64 kilobytes, the extent of the
+buffer you receive will not cross a 64K boundry.
+
+To unmap and free such a DMA region, you call:
 
 	pci_free_consistent(dev, size, cpu_addr, dma_handle);