OK, solved this one myself (sort of) : o Using the command line options: ... -append 'root=/dev/sda rw selinux=0 enforcing=0 console=ttyS0' -m 2048 -k en-gb -nographic -vga none -vnc none -enable-kvm -serial stdio -nodefaults does get the kernel to launch the console on stdio . So doing : $ qemu-kvm ... -append 'root=/dev/sda rw selinux=0 enforcing=0 console=ttyS0' -m 2048 -k en-gb -nographic -vga none -vnc none -enable-kvm -serial stdio -nodefaults \ <$MY_INPUT_PIPE >/tmp/$MY_OUPUT_PIPE 2>&1 does have exactly the effect I want . Hooray! (where '...' are the other qemu-kvm arguments in quoted mail, and $MY_*PIPE are /tmp/el6x32.in and /tmp/el6x32.out as in previous mail. The above command works, so I can do: $ cat $MY_OUTPUT_PIPE &' $ cat >>$MY_INPUT_PIPE and I get a login prompt. But I still can't understand why this does not have the desired effect: $ qemu-kvm ... -append 'root=/dev/sda rw selinux=0 enforcing=0 console=ttyS0' -m 2048 -k en-gb -nographic -vga none -vnc none -enable-kvm -nodefault -chardev 'pipe,id=0,path=/tmp/el6x32' No output is produced on the output pipe after connecting a writer to the input pipe. I'd like to understand how the '--chardev pipe,path=...' option is meant to work if it does not have the effect of '-serial stdio' with I/O redirected to the pipes. On 05/01/2015, Jason Vas Dias <jason.vas.dias@gmail.com> wrote:
Aha! Thank you. Yes that does prevent the default stdio console . But no output appears on the input pipe, and outputting to input end has no effect: In one terminal, I do: $ cat /tmp/el6x32.out in the main terminal, I run: $ /usr/libexec/qemu-kvm -M rhel6.4.0 -cpu n270 -smp 1 -hda /home/rpmbuild/OEL6/img/OEL6_32.img -kernel /home/rpmbuild/OEL6/boot/vmlinuz-2.6.39-400.215.14.el6uek.i686 -initrd /home/rpmbuild/OEL6/boot/initramfs-2.6.39-400.215.14.el6uek.i686.img -append 'root=/dev/sda rw selinux=0 enforcing=0 console=0' -m 2048 -k en-gb -nographic -vga none -vnc none -enable-kvm -chardev pipe,id=0,path=/tmp/el6x32 -chardev tty,id=1,path=/dev/pts/4 -monitor stdio -nodefaults QEMU 0.12.1 monitor - type 'help' for more information (qemu) info status VM status: running (qemu)
In another terminal I connect to the input pipe: $ cat >>/tmp/el632.in
But no output appears on the /tmp/el6x32.out pipe , regardless of what is typed on the input pipe .
I want to issue the login commands and then set up the shell to run commands echo'ed to the input pipe on the physical - eg. : $ echo 'ls' > /tmp/el6x32.in and read the output from the guest on the output pipe: $ cat /tmp/el632.out
Anyone know any way of doing this ?
I'm trying to run a nested guest in a VMware guest whose physical host CPU has VMX enabled using qemu-kvm, but guest virtual networking is disabled in VMware so I can't use ssh / telnet in the guest to run commands .
Thanks for any further replies, Jason
On 05/01/2015, Michal Privoznik <mprivozn@redhat.com> wrote:
On 05.01.2015 15:03, Jason Vas Dias wrote:
Please can anyone enlighten me as to why linux qemu-kvm always creates the console on my terminal, when I am trying to direct all of its input and output to a pipe ?
I have created : $ mkfifo /tmp/el6x32{.in,.out,.monitor} and use the command: $ /usr/libexec/qemu-kvm -M rhel6.4.0 -cpu n270 -smp 1 \ -hda /home/rpmbuild/OEL6/img/OEL6_32.img \ -kernel /home/rpmbuild/OEL6/boot/vmlinuz-2.6.39-400.215.14.el6uek.i686 \ -initrd /home/rpmbuild/OEL6/boot/initramfs 2.6.39-400.215.14.el6uek.i686.img \ -append 'root=/dev/sda rw selinux=0 enforcing=0 console=0' \ -m 2048 -k en-gb -nographic -vga none -vnc none -enable-kvm \ -chardev pipe,id=0,path=/tmp/el6x32 -monitor pipe:/tmp/el6x32.monitor
But this ends up with the kernel's console on qemu-kvm's STDIO .
I actually want the console to be redirected to take input from /tmp/el6x32.in and direct output to /tmp/el6x32.out - I thought that was what the above '-chardev pipe,id=0,path=/tmp/el6x32' should do if kernel boot params 'console=0' is also supplied ? Why isn't this happening for me ? Anyone got a guest to read console input from a pipe and direct console output to a pipe ? If so, how?
Thanks in advance for any replies, Jason.
That's probably because qemu by default creates some serial/parallels/virtual console/... You may want to pass '-nodefaults' onto qemu-kvm command line.
Michal