tree e2211e1d5c894c29e92d4c744f504b38410efe41
parent 71d28e6c285548106f551fde13ca6d589433d843
author Chris Zankel <chris@zankel.net> 1202851027 -0800
committer Chris Zankel <chris@zankel.net> 1202953303 -0800

[XTENSA] Add support for configurable registers and coprocessors

The Xtensa architecture allows to define custom instructions and
registers. Registers that are bound to a coprocessor are only
accessible if the corresponding enable bit is set, which allows
to implement a 'lazy' context switch mechanism. Other registers
needs to be saved and restore at the time of the context switch
or during interrupt handling.

This patch adds support for these additional states:

- save and restore registers that are used by the compiler upon
  interrupt entry and exit.
- context switch additional registers unbound to any coprocessor
- 'lazy' context switch of registers bound to a coprocessor
- ptrace interface to provide access to additional registers
- update configuration files in include/asm-xtensa/variant-fsf

Signed-off-by: Chris Zankel <chris@zankel.net>