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 UART3
In fact when I go see in to /proc/tty/driver and I do a cat on OMAP-SERIAL Im able to see this
serinfo:1.0 driver revision:
0: uart:OMAP UART0 mmio:0x4806A000 irq:72 tx:0 rx:0 CTS|DSR|CD
1: uart:OMAP UART1 mmio:0x4806C000 irq:73 tx:0 rx:0 CTS|DSR|CD
2: uart:OMAP UART2 mmio:0x49020000 irq:74 tx:268 rx:37 RTS|CTS|DTR|DSR|CD
3: uart:OMAP UART3 mmio:0x49042000 irq:80 tx:0 rx:0 CTS|DSR|CD
I 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_normal
The 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 0x4806a000
setserial: can't set serial info: Invalid argument
While 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:vtmaster
sdio_uart /dev/ttySDIO 249 0-7 serial
acm /dev/ttyACM 166 0-31 serial
ttyprintk /dev/ttyprintk 5 3 console
OMAP-SERIAL /dev/ttyO 253 0-3 serial
serial /dev/ttyS 4 64-95 serial
pty_slave /dev/pts 136 0-1048575 pty:slave
pty_master /dev/ptm 128 0-1048575 pty:master
unknown /dev/tty 4 1-63 console
Basically 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 them
On 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/ttyS0
I get
-bash: echo: write error: Input/output error
I 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:0
1: uart:unknown port:00000000 irq:0
2: uart:unknown port:00000000 irq:0
3: uart:unknown port:00000000 irq:0
also 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_normal
I managed to do serial communication with muliples ports usig grml image on a x86 architecture. So its seems my 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.
