[PATCH 1/2] arm: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6

[Russell King - ARM Linux]

On Wed, Jun 23, 2010 at 10:39:13AM +0300, Tony Lindgren wrote:
> Yeah that can be done for __kuser_get_tls if it's always writable.
> But __switch_to is trickier because of the CONFIG_MMU ifdefs there.

And impossible with XIP kernels.

> What if we have optional __switch_to and __kuser_get_tls implementations
> in the mm/proc-*.S files that get copied over the current locations
> if implemented?

Also problematical with XIP - if we go down the route of implementing
these by copying code fragments into the kernel, we need to strip out
XIP support or implement a second way.  Obviously having a second way
adds maintainence burden, and the second way will probably lose out
on updates.