On 05/07/2016 12:07, Daniel P. Berrange wrote: >> > What the final default behavior will be is not clear yet. Not enabled? >> > Enabled in case no VGA is present? Enabled unconditionally (simliar to >> > ovmf)? > (Bitter) experiance in libvirt has shown us that magically enabling > things based on whether or not some other feature is enabled leads > to pain and suffering in the long term. > > So from libvirt's POV, we would like an explicit command line flag > to turn on/off seabios serial console support, with no dependancy > on whether VGA is present or not.
With my other proposal, "-machine graphics=no -device sga" should do it. However, for libvirt to do this, it should stop using "-nographic" to disable all display backends, and instead use "-display none". The advantage is that neither "-display none" nor "-machine graphics=no" do any magic redirection of the monitor and the serial ports to stdio. "-display none" is supported since QEMU 1.0. For old QEMU without query-command-line-options it can be scraped from help text; for new QEMU with query-command-line-options it can be treated as always there. Paolo