Hi, 2012/4/18 夏业添 <summerxyt@xxxxxxxxx>: > Hi Dave, > > Thanks for reply. My English is not very good, and so I want to ask about a > term:map. Does map mean that create a relationship between the virtual space > and physical memory? In this case yes. The MMU translates virtual addresses to physical addresses. So when dealing with linux you have a virtual memory space, and a totally separate physical memory space. The MMU translates (or maps) virtual addresses to physical addresses. alloc_vm_space allocates some address space from virtual memory, but doesn't set up any mapping to physical memory. So the complete process of allocating memory goes something like this: 1 - Allocate some virtual address space 2 - Allocate some physical pages 3 - Setup the MMU to map your virtual address space to the physical pages. alloc_vm_pages just does step 1. vmalloc and kmalloc do steps 1, 2, and 3 -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
