On 2/22/07, Robert P. J. Day <rpjday@xxxxxxxxxxxxxx> wrote:
i'm trying to understand the distinction (if there *is* one) between logical and virtual addresses in kernel space. according to the LDD3 book, logical addresses are most likely treated like physical addresses, and might differ from the actual physical addresses only by a constant offset. (e.g., logical addresses in the 3G-4G range might just be reduced by 3G to map into the first physical 1G of memory, something simple like that.) in any case, even with something this simple, there is still a page mapping operation going on. on the other hand, LDD3 describes kernel *virtual* addresses as "similar" to logical addresses, but possibly without the linear, one-to-one mapping to physical addresses that logical addresses have. so is there a meaningful difference between these two types of addresses other than a philosophical one? are they treated any differently in terms of page mapping? i'm just curious.
As far as I can understand, Virtual addresses are superset of Logical addresses. Logically consequtive memory will also be physically continuous, but virtually continuous memory is not guaranteed to be physically continuous. It seems to me that Logical addresses refer to all addresses in the Normal and DMA memory Zone; and High memory mappings / temporary mappings come under Virtual addresses. Somebody please CMIIW Thanks, Rajat -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
