> Thanks for your replied. I surveyed in the internet and found the > kerenl's kmalloc API also return a continuous memory address. Is it > right? So there are two kernel APIs (__get_free_page, kmalloc) return > a _continuous_ memory address (virtual address) and it can be convert > to physical address by virt_to_phys().
Yes that's right, AFAIK kmap allocates physically contiguous memory and vmalloc allocates virtual contiguous memory. Actually the 2 functions you're pointing out (__get_free_page and kmalloc) are not independent. At its heart, the kernel allocator is page based so kmalloc uses the same page based functions to allocate is memory - infact the kmalloc interface is built on top of the slab layer (which uses the page allocation functions to allocate memory), get_free_page is just at a much lower level. Out of curiosity, why do you need the physically addresses of the memory you're allocating for your particular application? Regards, -Joel -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecar...@nl.linux.org Please read the FAQ at http://kernelnewbies.org/FAQ
