On 06/06/2016 08:18 AM, Russell King - ARM Linux wrote: > On Sun, Jun 05, 2016 at 11:20:26PM -0400, Bill Mills wrote: >> Allow early-init to specify modifications to be made to the boot time page >> table. Any modifications specified will be done with MMU off at the same >> time that any Phy<->Virt fixup is done. > > I think this is rather over-engineered - do we need to support multiple > different fixups to the page tables like this?
Yes I was expecting this comment but thought I would give you the choice. :) > > Given how this has grown, I think it would be better to duplicate the > existing swapper_pg_dir, modify the new copy, and then have the > pv-fixup-asm code merely copy the new to the old with the MMU off. > That way, the only two things that the assembly code has to do is to > deal with the page table update, and updating the TTBR registers. > Most of the complexity can then be kept in the C code. > I really like this. I can just do the outer shared fixup and not worry about a generalized mechanism. *If* someone needs to do another fixup they can just code it in C. The new patch #1 will just rework the PV_FIXUP for the new asm/C split. You want the off-line table to copy over the early table in place w/ MMU off, correct? (Not update the HW to point to a new spot.) > I think we also need to modify the TTBCR to match the sharability of > memory - currently, TTB walks will be inner sharable, but my > understanding is that if we switch memory to be outer sharable, we > also need to update the TTB walks to match. > Good point, Thanks. I don't think our internal hack has been doing that.
