On Tue, Mar 3, 2009 at 11:39 AM, NAHieu <nahieu@xxxxxxxxx> wrote: > On Tue, Mar 3, 2009 at 12:16 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: >> This is the first time I have seen the word "unity-mapping"......if it >> is your invention....congratulations!!!! U have created a new term. > > so you learned a new term today :-). but i agree that it is not > popular, and it confused me at first. > > so the more popular one is "identity mapping", right? > > that is not my term, but somebody else. I read that on internet somewhere ... > >> >> Usually I heard of "identity mapping", "direct mapping", linear >> mapping, vs "non-linear mapping". The formula is basically >> equivalent to __pa(), and all the different variation: __va(), >> virt_to_page(), pfn_to_kaddr() etc. It is all just using a >> straightforward formula. This is because virtual address and >> physical addr are inter-convertible directly in the ZONE_NORMAL range. >> But not in the ZONE_HIGH area. kmalloc() always returned addresses >> in these range. All the confusing API like pud*, pgd*, pmd*() API >> also hinges on this characteristic to convert directly between >> physical and virtual, or to extract out page frame number, PTE etc >> from the virtual/physical addresses. > > OK, so the difference between kmalloc and vmalloc in term of address > they return: > - kmalloc() always return addresses in ZONE_NORMAL > - vmalloc() always returns addresses in ZONE_HIGH > > Could you confirm that is correct? to the best of my knowledge....i think yes. > > So my question now is: what is ZONE_NORMAL range? I mean from what > address to what address? > eh.....check header file definition......it varies from arch to arch, and may be modified at bootup time via some parameter as well. but don't have to know either - cannot find any reason for that. can i know why did u ask? > Thanks! > H > -- Regards, Peter Teoh -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
