On Thu, Nov 08, 2018 at 01:05:09PM +0100, Florian Weimer wrote: > Would it be possible to reserve a bit for PKEY_DISABLE_READ? > > I think the POWER implementation can disable read access at the hardware > level, but not write access, and that cannot be expressed with the > current PKEY_DISABLE_ACCESS and PKEY_DISABLE_WRITE bits. POWER hardware can disable-read and can **also disable-write** at the hardware level. It can disable-execute aswell at the hardware level. For example if the key bits for a given key in the AMR register is 0b01 it is read-disable 0b10 it is write-disable To support access-disable, we make the key value 0b11. So in case if you want to know if the key is read-disable 'bitwise-and' it against 0x1. i.e (x & 0x1) RP
