On Tue, Mar 3, 2009 at 2:41 PM, NAHieu <nahieu@xxxxxxxxx> wrote: > On Tue, Mar 3, 2009 at 3:29 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: >> - Show quoted text - >> 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? > > I am working on a tool to analyze the kernel memory, so I need to > understand how kernel manages and layouts its memory. > analyze the memory for what? patterns of allocation? patterns of API usages? or performance analysis of different APIs used? -- 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
