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? So my question now is: what is ZONE_NORMAL range? I mean from what address to what address? Thanks! H -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
