Hi Paul, Did you get serial ports working even in dom0 on Cubietruck yet? It took me quite a while to discover that Xen normally disables the A20 UARTs by deleting them from the device tree:
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/arm/platforms/sunxi.c;h=0ba7b3d9b476a95edb653e120b7b3900a47f7c06;hb=HEAD#l64 Luke On Wed, 7 Oct 2015 at 21:00 Paul Skentzos <[email protected]> wrote: > Dave, > > > On 10/6/2015 5:04 PM, David Scott wrote: > > Hi Paul, Aaron, > > > > On Tue, Oct 6, 2015 at 8:27 PM, Paul Skentzos < > [email protected] > > <mailto:[email protected]>> wrote: > > > > We are trying to access a serial port passed to a domu. We're very > new to Mirage > > and ocaml, but plan on converting our existing system to use > MirageOS for > > various domU's. > > > > So, at the moment, the question we have is whether anyone has had > any success > > writing to multiple serial ports with one of those serial ports > being accessed > > from a domu? > > > > As a first attempt, we took the Mirage console example and added a > second > > console. We connected it to '1' and then to /dev/null and tried to > print to it. > > Neither of the ideas were valid. We're not sure what the console > should be named > > or what the hashtbl is looking for. The application compiles, but > the VM halts > > with a message stating. "... waiting for hotplug". The application > built for > > unix didn't work either. > > > > > > We are trying to read data from a GPS receiver from a domu. > > > > > > Interesting! Is the GPS receiver connected to a physical serial port on > the host? > > > > Thanks for the quick response. Yes, the GPS is connected to the host, to a > hardware serial port. > > > The virtual serial ports that Mirage can see need to be served by > something on > > the host (a "backend", typically in dom0). If you're creating your VM > with "xl > > create" then you can declare "channels"[1] which will spawn a qemu > process in > > dom0 which will act as the server/backend. At the moment the backend can > only be > > connected to a fresh tty or a Unix domain socket -- there is no built-in > support > > for proxying to a real /dev/ttyS* device. > > > > I think the first thing to do is to verify that adding a 'channel' to > your xl > > config file causes the Xen domU to get further than "waiting for > hotplug". After > > that I think you could declare the backend to be a Unix domain socket, > and then > > run a proxy in dom0 which would write the data to the appropriate ttyS > device. > > > > Sorry that's a bit clunky -- when I added the channel support to "xl" I > didn't > > think about the possibility of a real serial port. I'm sure that could > be added > > in future though. > > > > What do you think? > > > > This is really good information and you were speaking the language my > colleague > and I were as we iterated through the design. > > Here are our results. Running the system on an x86 VM worked just as you > described above, so that was great news. However, and we should have been > clear > about this at the beginning, our hardware platform is ARM based; > Cubietruck, > specifically. We tried the same process on the Cubietruck and it did not > work. > I'm assuming that this is the case since ARM does not make use of qemu > like x86 > does. > > It seems that this could be overcome on ARM, however not without some > difficulty. Any thoughts on this? > > Best regards, > Paul > > > > Cheers, > > Dave Scott > > > > [1] http://xenbits.xen.org/docs/unstable/misc/channel.txt > > > > > > Any ideas where we should look for getting this capability? > > > > I appreciate the help! > > > > Paul Skentzos > > Aaron Cornelius > > > > > > > > > > > > _______________________________________________ > > MirageOS-devel mailing list > > [email protected] <mailto: > [email protected]> > > http://lists.xenproject.org/cgi-bin/mailman/listinfo/mirageos-devel > > > > > > > > > > -- > > Dave Scott > > _______________________________________________ > MirageOS-devel mailing list > [email protected] > http://lists.xenproject.org/cgi-bin/mailman/listinfo/mirageos-devel >
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