• Paul Mackerras's avatar
    powerpc/mm/book3s-64: Free up 7 high-order bits in the Linux PTE · f1a9ae03
    Paul Mackerras authored
    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: default avatarPaul Mackerras <paulus@samba.org>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    f1a9ae03
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