Cannot start second console

[claude4334]

There seems to be an issue with multiple consoles. Specifying in a lab.conf file the "A[con1]=xterm" directive does not raise an error, but does not open the second terminal on host A either.

Thank you
Claude.

[kartoch]

Testing it:

$  vstart --con1=xterm dummy

============= Starting virtual machine "dummy" =============
   Kernel:     /home/kartoch/works/netkit/netkit-ng/kernel/netkit-kernel
   Modules:    /home/kartoch/works/netkit/netkit-ng/kernel/modules
   Memory:     32 MB
   Model fs:   /home/kartoch/works/netkit/netkit-ng/fs/netkit-fs
   Filesystem: /home/kartoch/tmp/dummy.disk (new)
   Hostfs at:  /home/kartoch

Running ==> xterm -e /home/kartoch/works/netkit/netkit-ng/kernel/netkit-kernel modules=/home/kartoch/works/netkit/netkit-ng/kernel/modules name=dummy title=dummy umid=dummy mem=36M ubd0=/home/kartoch/tmp/dummy.disk,/home/kartoch/works/netkit/netkit-ng/fs/netkit-fs root=98:0 uml_dir=/home/kartoch/.netkit/mconsole hosthome=/home/kartoch quiet con0=fd:0,fd:1 con1=xterm SELINUX_INIT=0

Parameters seems to be OK, so maybe it lacks kernel support ? A check of netkit-ng-kernel is needed...

[kartoch]

Trying to launch kernel with con0=xterm:

$ /home/kartoch/works/netkit/netkit-ng/kernel/netkit-kernel modules=/home/kartoch/works/netkit/netkit-ng/kernel/modules name=dummy title=dummy umid=dummy mem=36M ubd0=/home/kartoch/tmp/dummy.disk,/home/kartoch/works/netkit/netkit-ng/fs/netkit-fs root=98:0 uml_dir=/home/kartoch/.netkit/mconsole hosthome=/home/kartoch  con0=xterm SELINUX_INIT=0 

The system hangs after kernel boot:

Locating the bottom of the address space ... 0x10000
Locating the top of the address space ... 0xc0000000
Core dump limits :
    soft - 0
    hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
  - /proc/mm...not found: No such file or directory
  - PTRACE_FAULTINFO...not found
  - PTRACE_LDT...not found
UML running in SKAS0 mode
Adding 7794688 bytes to physical memory to account for exec-shield gap

[kartoch]

Whatever I try, I have only one serial console enabled:

console [tty0] enabled
Initializing software serial port version 1

[kartoch]

I think i found it: xterm mode requires port-helper program from uml-utilities. I removed it from original Netkit but it seems it is needed INSIDE the machines. I will try next monday, but if you need a fix for the WE, you can try to add the uml-utilities in packages-list file (inside netkit-ng-build/fs/) and rebuild the fs.

See more UML documentations at http://lxr.free-electrons.com/source/Documentation/virtual/uml/UserModeLinux-HOWTO.txt

[claude4334]

Hi,

sorry I wasn't much of a help this week, I did not have time to test it. Thank you for finding the solution ! I'll try it this week-end. Don't worry about the release (for me at least), no hurry.

Best,
Claude.

[kartoch]

That's not the solution: I was unable to open a second term even when uml-utilities is installed on the UML machines. Reading again various UML docs, I found that port-helper must be on the host.

I've posted messages on UML ML, hope someone can help me.

[nopid]

The filesystem is missing ttys in /dev :

$ vstart --con1=xterm tadam
tadam# mknod -m 600 /dev/tty1 c 4 1
tadam# echo Hello world > /dev/tty1
tadam# cat < /dev/tty1

I can see the xterm pop when writing to /dev/tty1 for the first time and communication goes both ways. In order to get a full console in the new xterm, /etc/inittab should be modified to add a new line (following netkit original filesystem):
2:23:respawn:/sbin/mingetty --noclear --noissue --autologin root tty1

To test it right away: tadam# kill -HUP 1

Alas for some reason when I reboot the machine with these modification the kernel panics... Maybe a race condition somewhere?
$ vstart --con0=this --con1=xterm tadam

PS. Testing with stock i386 versions from the netkit-ng homepage (kernel K3.2 filesystem F7.0) on a x86_64 host.

[nopid]

FYI: the race problem is a kernel issue: the bug does not appear when replacing the netkit-ng-kernel binary with 32-bit or 64-bit kernels from http://uml.devloop.org.uk/