fbuffer: Implement RFILL as an accelerated primitive

By implementing RFILL as an primitive, we can get a huge
speed-up of the screen erasing function. On board-js2x,
it writes the pattern directly into the IO region, and on
board-qemu it uses the KVMPPC_H_LOGICAL_MEMOP hypercall to
copy the pattern from a temporary buffer into the IO region.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
6 files changed