• Chris Zankel's avatar
    [XTENSA] Add support for configurable registers and coprocessors · c658eac6
    Chris Zankel authored
    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: default avatarChris Zankel <chris@zankel.net>