Hi Friends,
Please help me to figure out some basic concepts in MM.
From the books, i learned that VMA to PA translation consists of traversing the full page directory, which consists of Global Directory, Middle Directory and Page Table.
I have also read that, VMA to PA translation is done using a macro virt_to_page defined as given below.
#define virt_to_page(kaddr) (mem_map + (__pa(kaddr) >> PAGE_SHIFT))
If there is a macro, why we need code for traversing all the page directories ?. This macro is a simple math, which points to an index in global mem_map array, which contains all the pages in the system.
So my doubts are,
Is the macro only for ZONE_NORMAL (upto 896M, which is directly mapped by kernel) memory pages ?.
Is mem_map array contains pages upto ZONE_NORMAL ?
Is page traversing happens only for HIGH_MEM ?.
Regards,
Shameem
Please help me to figure out some basic concepts in MM.
From the books, i learned that VMA to PA translation consists of traversing the full page directory, which consists of Global Directory, Middle Directory and Page Table.
I have also read that, VMA to PA translation is done using a macro virt_to_page defined as given below.
#define virt_to_page(kaddr) (mem_map + (__pa(kaddr) >> PAGE_SHIFT))
If there is a macro, why we need code for traversing all the page directories ?. This macro is a simple math, which points to an index in global mem_map array, which contains all the pages in the system.
So my doubts are,
Is the macro only for ZONE_NORMAL (upto 896M, which is directly mapped by kernel) memory pages ?.
Is mem_map array contains pages upto ZONE_NORMAL ?
Is page traversing happens only for HIGH_MEM ?.
Regards,
Shameem
