I'm running an Linux Image (kernel 3.2.8) for beagleboard-xm on QEMU's 1.4.0 emulator Ubuntu distribution for 13.04. My image is created using Buildroot beagle_defconfig. I added some pkgs to be able to debug a little.QEMU call cmd:`$ sudo qemu-system-arm -M beaglexm -m 1024 -sd ./test.img -clock unix -serial stdio -device usb-mouse -device usb-kbd -serial pty -serial pty`[sudo] password for emperador: char device redirected to /dev/pts/3 (label serial1)char device redirected to /dev/pts/4 (label serial2)What I want to do is to have a communication between guest and host across serial the 4 differents ttyO present on the guest. QEMU offer facilities to redirect the trafic to some device in the host side. My problem goes like this:At the guest kernel boot Im able to see that my UART where enabled[    2.682040] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled[    2.777947] omap_uart.0: ttyO0 at MMIO 0x4806a000 (irq = 72) is a OMAP UART0[    2.794967] omap_uart.1: ttyO1 at MMIO 0x4806c000 (irq = 73) is a OMAP UART1[    2.814942] omap_uart.2: ttyO2 at MMIO 0x49020000 (irq = 74) is a OMAP UART2[    2.966825] console [ttyO2] enabled[    2.984777] omap_uart.3: ttyO3 at MMIO 0x49042000 (irq = 80) is a OMAP UART3In fact when I go see in to /proc/tty/driver and I do a cat on OMAP-SERIAL Im able to see thisserinfo:1.0 driver revision:0: uart:OMAP UART0 mmio:0x4806A000 irq:72 tx:0 rx:0 CTS|DSR|CD1: uart:OMAP UART1 mmio:0x4806C000 irq:73 tx:0 rx:0 CTS|DSR|CD2: uart:OMAP UART2 mmio:0x49020000 irq:74 tx:268 rx:37 RTS|CTS|DTR|DSR|CD3: uart:OMAP UART3 mmio:0x49042000 irq:80 tx:0 rx:0 CTS|DSR|CDI know that ttyO2 is working because my console is been redirected to it. The thing is that doing a set serial on any of the ttyO I get the following message: [root@enu driver]# setserial -a /dev/ttyO0/dev/ttyO0, Line 0, UART: undefined, Port: 0x0000, IRQ: 72    Baud_base: 3000000, close_delay: 50, divisor: 0    closing_wait: 3000    Flags: spd_normalThe same goes with ttyO2.I tried to set some settings to any of the ttyO with setserial but I always get the same message:[root@enu ~]# setserial /dev/ttyO0 uart 8250                              setserial: can't set serial info: Invalid argument[root@enu ~]# setserial /dev/ttyO0 port 0x4806a000setserial: can't set serial info: Invalid argumentWhile looking at guest /proc/tty/drives this is what we see/dev/tty             /dev/tty        5       0 system:/dev/tty/dev/console         /dev/console    5       1 system:console/dev/ptmx            /dev/ptmx       5       2 system/dev/vc/0            /dev/vc/0       4       0 system:vtmastersdio_uart            /dev/ttySDIO  249 0-7 serialacm                  /dev/ttyACM   166 0-31 serialttyprintk            /dev/ttyprintk   5       3 consoleOMAP-SERIAL          /dev/ttyO     253 0-3 serialserial               /dev/ttyS       4 64-95 serialpty_slave            /dev/pts      136 0-1048575 pty:slavepty_master           /dev/ptm      128 0-1048575 pty:masterunknown              /dev/tty        4 1-63 consoleBasically I want to establish a serial communication between a guest and a host, but the serial ports on the guest side aren't well configured./sys/class/tty show that tty drivers had been linked to a serial device.has I showed up before, only omap uarts have been initialized and attached to ttyO*. notice that the console is been redirected ttyO2 by kernel configs. but because I added -serial stdio, console is been redirected to the terminal that invoked QEMU.If I redirect the console using at first -serial pty instead of -serial stdio , I'm able to prompt the console in minicom by opening the pty created on the host side. Still nothing happen on the others pty created on the host side to communicate across other ports.On host side I open /dev/pts/3 and /dev/pts/4 with minicom or by doing cat on themOn guest side:Whent I do echo test > /dev/ttyO0 or 1 or 3 nothing. but when I do it on ttyO2, test prompt on the console terminal (which is normal).now when using any of the ttyS:echo test > /dev/ttyS0I get-bash: echo: write error: Input/output errorI made some research about this error and what I found is that is could be many things. But one thing that I noticed was that no device beside serial has been assigned to ttyS. and looking at /proc/tty/driver/serial we see this :serinfo:1.0 driver revision:0: uart:unknown port:00000000 irq:01: uart:unknown port:00000000 irq:02: uart:unknown port:00000000 irq:03: uart:unknown port:00000000 irq:0also setserial -a /dev/ttyS0 confrim this:/dev/ttyS0, Line 0, UART: unknown, Port: 0x0000, IRQ: 0    Baud_base: 0, close_delay: 50, divisor: 0    closing_wait: 3000    Flags: spd_normalI managed to do serial communication with muliples ports usig grml image on a x86 architecture. So its seems the host side is fine.If anyone have ever made something like this work before on QEMU -M beaglexm or any other ARM architecture, I would gladly take any details on the VM used, QEMU's version and distribution as well as the kernel details and image configs used.
ttyO ports do not have the good port address on QEMU 1.4.0 running image for beagleboard-xm
virtual machine;embedded;virtualization;qemu;serial port
I found what my problem was, QEMU ins't mapping the serial chardev of any extra -serial pty.After doing the this Invoke command:sudo qemu-system-arm -M beaglexm -m 1024 -sd ./test.img -clonix -serial stdio -device usb-mouse -device usb-kbd -serial pty -serial pty -monitor ptychar device redirected to /dev/pts/5 (label compat_monitor0)char device redirected to /dev/pts/7 (label serial1)char device redirected to /dev/pts/10 (label serial2)We can see that 2 extra serials where created with the label serial 1 and 2.But if I look at the tree info (qemu) info qtreedev: omap_uart, id uart4    revision = 82    mmio_size = 4096    baudrate = 812500    chardev = uart4    irq 3    mmio 0000000049042000/0000000000001000  dev: omap_uart, id uart3    revision = 82    mmio_size = 4096    baudrate = 812500    chardev = serial0    irq 3    mmio 0000000049020000/0000000000001000  dev: omap_uart, id uart2    revision = 82    mmio_size = 4096    baudrate = 812500    chardev = uart2    irq 3    mmio 000000004806c000/0000000000001000  dev: omap_uart, id uart1    revision = 82    mmio_size = 4096    baudrate = 812500    chardev = uart1    irq 3    mmio 000000004806a000/0000000000001000We clearly see that just the label serial0 was attached to a uart (the one setted to be the console). The other labels (serial1 and serial2) are no where to be found.With the working image of grml that jofel was realy nice to tell me we see this:  dev: i440FX-pcihost, id     irq 0    bus: pci.0      type PCI      dev: PIIX3, id         addr = 01.0        romfile = <null>        rombar = 1        multifunction = on        command_serr_enable = on        class ISA bridge, addr 00:01.0, pci id 8086:7000 (sub 1af4:1100)        bus: isa.0          type ISA          dev: isa-serial, id             index = 2            iobase = 0x3e8            irq = 4            chardev = serial2            wakeup = 0            isa irq 4          dev: isa-serial, id             index = 1            iobase = 0x2f8            irq = 3            chardev = serial1            wakeup = 0            isa irq 3          dev: isa-serial, id             index = 0            iobase = 0x3f8            irq = 4            chardev = serial0            wakeup = 0            isa irq 4all 3 serial lebels were attached to a chardev.Now I just have to ask a new question about how making QEMU to link those lables to my beagleboard uarts.Also I would like to add I think that setserial did not outputed any info about ttyO's because it doesn't support omap uarts. setserial ? shows what devices are supported. In the case of the ttyS's, I think its because the tty drivers are installed but there is no other type of uarts bisede omap uarts emulated for bealgeboard in QEMU.Thanks alot for everyone that took a look on this question and specialy jofel.