I know that in ARM processor's MMU, some bits such as referenced bit or dirty bits are not provided in PTE. And as a result two page tables are provided in these systems – the processor-native page tables, with neither referenced bits nor dirty bits, and software-maintained page tables with the required bits present. However, my question is since there is no validity bit in the processor-native page table, how does the MMU figure out the translation is invalid, and generates a page fault?
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"since there is no validity bit in the processor-native page table" - er, really? If you look at the ARM PTE format there's most definitely an "Invalid" PTE type there. OK, so perhaps two bits is not technically *a* bit in the most mind-numbingly pedantic sense, but still... – Notlikethat Mar 22 '16 at 17:36
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Thank you @Notlikethat , – Hoda Mar 23 '16 at 17:40
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Possible duplicate of [How does ARM Linux emulate the dirty, accessed, and file bits of a PTE?](http://stackoverflow.com/questions/32943129/how-does-arm-linux-emulate-the-dirty-accessed-and-file-bits-of-a-pte) – artless noise Mar 24 '16 at 02:36