Hi... On Jan 11, 2008 12:27 PM, sahlot arvind <asahlot@xxxxxxxxx> wrote: > Hi All, > > I just started learning Linux Virtual Memory Management Subsystem. > I see the memory is divided into three zones. Comments in file mm/mmzone.h > > /* > * ZONE_DMA < 16 MB ISA DMA capable memory > * ZONE_NORMAL 16-896 MB direct mapped by the kernel > * ZONE_HIGHMEM > 896 MB only page cache and user processes > */ > > Here second comment (ZONE_NORMAL) says that it is directly mapped by kernel. > Could anybody please tell me what does direct mean here? > Does this mean Physical address = Virtual Address??? More precisely, it means identical mapping, or virtual address =physical address + PAGE_OFFSET for pages that resides in the ZONE_NORMAL. Pay attention, in 64 bit there isn't ZONE_HIGHMEM...all pages are in ZONE_NORMAL. regards, Mulyadi. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
