Good!! Thanks a lot, Denis. 2010/12/23 Denis Kirjanov <kirjanov@xxxxxxxxx>: > On Thu, Dec 23, 2010 at 6:10 PM, Gustavo da Silva > <gustavodasilva@xxxxxxxxx> wrote: >> Hi Everyone! >> >> Friends, could someone explain me the difference between Kernel Logical >> and Kernel Virtual Address? > > > AFAIK there are 3 types of addresses: physical, kernel virtual > (one-to-one mapped), > and ...user virtual addresses... > Lets assume x86_32 for simplicity: > > ========================== > +kernel part (identity-mapped) + > ========================== <---- PAGE_OFFSET protection boundary > + + > + user portion(THREAD_SIZE)+ > + + > ========================== > Kernel works on behalf of the user address space (think about that one > part of the user space is > always the same for each process - kernel part). Kernel portion (at > PAGE_OFFSET and above) translates address > using simple formula: > kernel virtual addr - PAGE_OFFSET > > Things are different for the bottom half of the virtual address space > (THREAD_SIZE portion). > This is a MMU time :) > Here well-known translation process (using page tables) of the virtual > address to physical one begins. > >> I'm reading Linux Device Drivers 3th, but I did not understand about that. >> >> I have a macro vision about Kernel Virtual Address (virtual address is used >> do hide the paging mechanism and physical memory, I think), and Linear >> is the address used in to evaluate to the physical (using page >> directory+page table+offset). >> >> But and the Kernel Logical Address? Why Logical Address is Virtual >> Address, but not all >> Virtual Address is a Logical Address? >> >> Regards. >> >> Atenciosamente, >> >> Gustavo da Silva >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> > > > > -- > Regards, > Denis > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
