On 11/01/13 16:23, Andreas Färber wrote: > Am 11.01.2013 16:00, schrieb Peter Maydell: >> On 11 January 2013 13:42, Wolfgang Mauerer <wolfgang.maue...@siemens.com> >> wrote: >>> The configuration register for the onboard LEDs is >>> emulated, but the state is not exported, which makes >>> the feature not particularly useful. Create a character >>> device to make status changes accessible to the host. >>> >>> For example, use the command line argument >>> >>> -chardev socket,id=leds,host=localhost,port=12345,server,nowait >>> >>> to observe status changes via a socket. >> >> This isn't the only board we emulate which has LEDs. I'd >> rather see this problem tackled with a general plan for "this >> is how we handle LEDs in QEMU boards" rather than a >> versatile board specific patch. > > Hm, mips_malta.c does use a CharDriverState... just a more "structured" > one using ASCII art.
that's one of the reaons why I used a character device to export the status information. However, a simple custom protocol (or maybe the same information in JSON) seemed more appripriate since I assume that graphical frontends will eventually visualise the LED status. Having to parse some ASCII art output for this seems suboptimal. Exporting a binary QOM property (as you suggested in another email) might be an option, although I'm not really sure if LED status changes should be communicated this way -- to me, using a chardev feels nicer. Do the QMP maintainers have an opinion? Regards, Wolfgang
