path: root/arch/powerpc/include/asm/nohash/64/pgtable.h
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authorPaul Mackerras <>2016-02-22 13:41:13 +1100
committerMichael Ellerman <>2016-02-27 21:06:57 +1100
commitf1a9ae034a263d93ea408825afe699aebf37010a (patch)
tree2c62d7e3d505ff4f260da8e154e5d8968330ef2c /arch/powerpc/include/asm/nohash/64/pgtable.h
parent1ec3f937102154b54c3ba97b79d4bd3931bb0eaa (diff)
powerpc/mm/book3s-64: Free up 7 high-order bits in the Linux PTE
This frees up bits 57-63 in the Linux PTE on 64-bit Book 3S machines. In the 4k page case, this is done just by reducing the size of the RPN field to 39 bits, giving 51-bit real addresses. In the 64k page case, we had 10 unused bits in the middle of the PTE, so this moves the RPN field down 10 bits to make use of those unused bits. This means the RPN field is now 3 bits larger at 37 bits, giving 53-bit real addresses in the normal case, or 49-bit real addresses for the special 4k PFN case. We are doing this in order to be able to move some other PTE bits into the positions where PowerISA V3.0 processors will expect to find them in radix-tree mode. Ultimately we will be able to move the RPN field to lower bit positions and make it larger. Signed-off-by: Paul Mackerras <> Signed-off-by: Michael Ellerman <>
Diffstat (limited to 'arch/powerpc/include/asm/nohash/64/pgtable.h')
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