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): https://content.riscv.org/wp-content/uploads/2016/07/riscv-privileged-v1.9-1.pdf 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. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx
