[PATCH v2 11/12] ARM: wire up UEFI init and runtime support

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Nov 16 11:48:13 PST 2015

On Mon, Nov 16, 2015 at 08:04:00PM +0100, Ard Biesheuvel wrote:
> OK. So you mean set TTBR to the zero page, perform the TLB flush and
> only then switch to the new page tables?

Not quite.

If you have global mappings below TASK_SIZE, you would need this
sequence when switching either to or from the UEFI page tables:

- switch to another set of page tables which only map kernel space
  with nothing at all in userspace.
- flush the TLB.
- switch to your target page tables.

As I say in response to one of your other patches, it's probably
much easier to avoid any global mappings below TASK_SIZE.

FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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