On Wed, Oct 12, 2016 at 12:18:50AM +0200, Torbjörn Granlund wrote:
> PS. Does RISC-V have some sort of wait-for-interrupt instruction? I
> mean, an instruction suitable for the kernel idle loop which waits for
> interrupt, allowing hardware and simulators to save energy. If not, one
> should be proposed to the UCB folks.
The current privspec 1.9 (draft):
defines a WFI instruction, literally Wait For Interrupt (section 3.2.2).
However IIRC the reason qemu-system-riscv busy-waits is nothing to do
with this, it's because the interim device model is a big hack. Soon
to be replaced with virtio, we are all hoping.
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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