Vijay Tandeker | 29 Aug 15:18 2015

[uml-user] UML console not coming

Hi All,
    I am Vijay, working as software engineer in Tejas Networks Bangalore, India.

    I downloaded the following:
    - UML Kernel image v3.18 for i386 32 bit
    - root filesystem for Ubuntu-14 and Fedora21

 My system configuration:
 - Ubuntu-14.04 32 bit
 - Kernel : 3.19

 After downloading ran the following command:
 ./kernel ubda=Ubuntu_root_fs

 After sometime, Got the following error continuously:
 - getmaster : no usable host pty device

 I am unable to get the console.

 I searched in internet about the solution but no luck. Tried with Fedora root_fs also but no success.

 Please help.

Regards,
Vijay

 
------------------------------------------------------------------------------
Mark Morgan Lloyd | 27 Aug 15:14 2015
Picon

[uml-user] 64-bit UML with 32-bit root

The (unofficial?) FAQ at http://uml.devloop.org.uk/faq.html implies that 
it is possible to build UML on a 64-bit system to run a 32-bit guest.

The best that I can manage on e.g. Debian "Jessie" x86-64 is to use 
make ARCH=um SUBARCH=i386  which results in a 32-bit ELF to presumably 
run a 32-bit guest. Prerequisites appear to be the multiarch-support 
  and gcc-multiarch packages.

Is it possible to build UML as a 64-bit binary, but to run a 32-bit 
guest? What I'd like to be able to do is to put it on a system which has 
no multiarch stuff, i.e. to completely sequester the 32-bit libraries 
etc. within the guest filesystem.

[Background: I used UML fairly heavily in the 2.4 era, but I'm a 
comparative newcomer to x86-64. I'm trying to avoid overuse of 
multi-arch stuff.]

--

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

------------------------------------------------------------------------------
Jon Foster | 14 Aug 20:25 2015

[uml-user] UML randomly hanging

I'm using a stock Debian 7 AMD-64 SMP install on a 8 core Intel Xeon
server, with 24GB of RAM. I'm using Debian's supplied UML kernel and
tools. "uname -a", from within the UML returns: "Linux lamp1 3.2.54 #2
Thu Feb 6 22:33:28 UTC 2014 x86_64 GNU/Linux". Using a command like:

linux.uml "umid=$MACHNAME" con0=null,fd:2 con1=fd:0,fd:1 \
         con=null ssl=null "mem=4096m" "eth0=tuntap,tap0" \
         hostfs=/var/local/umlhostfs "ubd0=$ROOT" "ubd1=$SWAP"

Obviosuly the environment variables are filled with appropriate values.

I'm running a Debian 5 LAMP stack inside the UML. "/tmp" is a regular
disk backed filesystem. It runs ok if its not doing anything. But even
then from time to time you'll get a second or two pause. If it gets  a
modest amount of traffic it will hang for a few minutes, and things just
get worse and worse from there.

While its idle I've seen "hrtimer" warnings with 9 or 10 digit
nanosecond counts. I think this is at the heart of my problem.

Anybody have any advice?

TIA - Jon

--

-- 
Sent from my Debian Linux workstation -- http://www.debian.org/intro/about

Jon Foster
JF Possibilities, Inc.
jon <at> jfpossibilities.com
(Continue reading)

Jon Foster | 14 Aug 20:35 2015

[uml-user] per-instance tmpfs backed memory file

I'm kind of new to the UML thing. I've read that every instance of UML
creates a temp file that represents the RAM of that instance. Its
obvious that putting that in a "tmpfs" would be very good, but I don't
want to mount a tmpfs on "/tmp", its used by too many other things and
the size restriction would cause problems.

I've read a "per-instance" tmpfs can be setup... but nowhere have I seen
how that's done. There doesn't appear to be any CLI switches for telling
UML where to put the temp file and $TMPDIR doesn't seem to do anything
for it.

I'm running stock Debian 7 64bit on Intel Xeons, with their supplied UML
packages. The UML kernel version is 3.2.54.

How can I tell UML to put its temp file somewhere else?

THX - Jon

--

-- 
Sent from my Debian Linux workstation -- http://www.debian.org/intro/about

Jon Foster
JF Possibilities, Inc.
jon <at> jfpossibilities.com
541-410-2760
Making computers work for you!

------------------------------------------------------------------------------
Sergei Antonov | 6 Aug 13:54 2015

[uml-user] Segmentation faults when UML is run under gdb

Hello!
I'm trying compile and run UML (version 4.1) on x86_64. It builds and
runs fine as a normal program. But when run under gdb, it produces
several segmentation faults.

This is how I build and run it (based on
http://user-mode-linux.sourceforge.net/hacking.html instructions and
disk image from http://fs.devloop.org.uk/ ):
cd linux &&
make mrproper &&
make mrproper ARCH=um &&
git checkout v4.1 &&
make defconfig ARCH=um &&
make -j6 ARCH=um &&
cd .. &&
gdb --args linux/linux ubda=BusyBox-1.13.2-amd64-root_fs mem=256m

And this is a complete gdb output:

===========================================================
GNU gdb (GDB) 7.9.1
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
(Continue reading)

Balaco Baco | 21 Jun 04:21 2015

[uml-user] Why it doesn't work on Ubuntu 14.04?

I'm remotely accessing an Ubuntu 14.04.2 machine. And now I'm trying to
run an UML in it, but it is always giving me some errors, and it
finishes with segfaults or coredumps.

For example, the end of output is:

=========================
request_module: runaway loop modprobe binfmt-464c
Starting init: /sbin/init exists but couldn't execute it (error -8)
Starting init: /etc/init exists but couldn't execute it (error -13)
request_module: runaway loop modprobe binfmt-464c
Starting init: /bin/sh exists but couldn't execute it (error -8)
Kernel panic - not syncing: No working init found.  Try passing init=
option to kernel. See Linux Documentation/init.txt for guidance.
CPU: 0 PID: 1 Comm: swapper Not tainted 3.13.11-ckt20 #1
Stack:
 69037e90 602e26cd 60260fa9 00000000
 69037e90 601b0c71 60260fa9 00000000
 60260fa9 00000000 69037ea0 60263274
Call Trace:
 [<60260fa9>] ? printk+0x0/0xa0
 [<601b0c71>] ? bust_spinlocks+0x0/0x4f
 [<60260fa9>] ? printk+0x0/0xa0
 [<60260fa9>] ? printk+0x0/0xa0
 [<60263274>] dump_stack+0x2a/0x2c
 [<6026071d>] panic+0x141/0x290
 [<602605dc>] ? panic+0x0/0x290
 [<600b7e82>] ? copy_strings+0x0/0x2b9
 [<600b93ec>] ? do_execve+0x53c/0x5a7
 [<600185ed>] ? try_to_run_init_process+0x0/0x66
(Continue reading)

Toralf Förster | 31 May 19:13 2015
Picon
Picon

[uml-user] BTRFS : starting an uml using BTRFS gives

I don't get it in moment, at a 64 bit Gentoo Linux (host is Linux t44 4.0.4-hardened-r3) I get :

$ /home/tfoerste/devel/linux/linux earlyprintk ubda=t44uml ubdb=/mnt/ramdisk/t44uml_swap
eth0=tuntap,tap0,72:ef:3d:b6:67:0c,192.168.1.254 mem=2000M con0=fd:0,fd:1 con=pts
umid=uml_t44uml softlockup_all_cpu_backtrace=1
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 environment variables for a tempdir...none found
Checking if /dev/shm is on tmpfs...OK
Checking PROT_EXEC mmap in /dev/shm...OK
bootconsole [earlycon0] enabled
PID hash table entries: 4096 (order: 3, 32768 bytes)
Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)
Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Memory: 2009296K/2048000K available (3008K kernel code, 673K rwdata, 892K rodata, 113K init, 173K bss,
38704K reserved, 0K cma-reserved)
NR_IRQS:15
clocksource itimer: mask: 0xffffffffffffffff max_cycles: 0x1d854df40, max_idle_ns: 3526361616960 ns
Calibrating delay loop... 5746.68 BogoMIPS (lpj=28733440)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 4096 (order: 3, 32768 bytes)
Mountpoint-cache hash table entries: 4096 (order: 3, 32768 bytes)
Initializing cgroup subsys blkio
Initializing cgroup subsys devices
Initializing cgroup subsys freezer
Checking that host ptys support output SIGIO...Yes
(Continue reading)

kobabo kobabo | 13 Apr 08:42 2015

[uml-user] UML for mips

Hi,

Is it possible to run UML on mips architecture?

Thanks,
Koba <at> <at>
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david jhon | 5 Mar 10:21 2015
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[uml-user] Making a module for user-mode-linux and debugging it with gdb

Hi,

I have been doing pretty hard since last few days to set up user-mode-linux in my ubuntu-14.04 LTS host. I am a noob on this and want to debug openvswitch kernel module by using user-mode-linux. Currently I am following these links to up my uml:
    http://www.opensourceforu.com/2010/09/user-mode-linux-setup-and-debug/
    http://www.landley.net/code/UML.html
    https://help.ubuntu.com/community/UserModeLinux

but after I run this command linux-3.13/linux rootfstype=linux-3.13/uml-root-trusty it is Aborted with the following  output:

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.../run/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 24801280 bytes to physical memory to account for exec-shield gap
Initialized stdio console driver
Using a channel type which is configured out of UML
setup_one_line failed for device 1 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 2 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 3 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 4 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 5 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 6 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 7 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 8 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 9 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 10 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 11 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 12 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 13 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 14 : Configuration failed
Using a channel type which is configured out of UML
setup_one_line failed for device 15 : Configuration failed
Console initialized on /dev/tty0
console [tty0] enabled
console [mc-1] enabled
VFS: Cannot open root device "98:0" or unknown-block(98,0): error -19
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(98,0)
CPU: 0 PID: 1 Comm: swapper Not tainted 3.13.0 #1
Stack:
 63037d50 00000002 60238906 00000002
 60238947 60147ad0 601ad287 00008001
 600d8900 63172000 63037d60 601af835
Call Trace:
 [<60147ad0>] ? bust_spinlocks+0x0/0x60
 [<601ad287>] ? printk+0x0/0xa0
 [<600d8900>] ? SyS_mount+0x0/0x110
 [<601af835>] dump_stack+0x2a/0x2c
 [<601ac99c>] panic+0x137/0x286
 [<601ac865>] ? panic+0x0/0x286
 [<60024ac0>] ? unblock_signals+0x0/0xb0
 [<600d89e8>] ? SyS_mount+0xe8/0x110
 [<601ad287>] ? printk+0x0/0xa0
 [<600d8900>] ? SyS_mount+0x0/0x110
 [<6000211b>] mount_root+0x0/0x82
 [<60015290>] ? do_one_initcall+0x0/0x190
 [<60015290>] ? do_one_initcall+0x0/0x190
 [<601429d0>] ? strcpy+0x0/0x30
 [<60002199>] mount_root+0x7e/0x82
 [<6000211b>] ? mount_root+0x0/0x82
 [<60142ab0>] ? strncmp+0x0/0x60
 [<60002380>] prepare_namespace+0x1e3/0x22b
 [<60024ac0>] ? unblock_signals+0x0/0xb0
 [<600d3f60>] ? SyS_dup+0x0/0x70
 [<60015290>] ? do_one_initcall+0x0/0x190
 [<60001c8b>] kernel_init_freeable+0x27c/0x297
 [<600011b7>] ? repair_env_string+0x0/0xbd
 [<6005325d>] ? finish_task_switch.isra.71+0x2d/0x80
 [<601ac1f5>] kernel_init+0x15/0x1b0
 [<60016d61>] new_thread_handler+0x81/0xb0

Aborted (core dumped)

Secondly. I did also install user-mode-linux and other relavant utilities with apt-get and when I run linux rootfstype=hostfs rw init=/bin/bash it works but I am not understanding how to compile my required module and debug it in this scenario.

I'll be really grateful for your help to get it fixed or your suggestions. Thank you in advance!

kind Regards;
david

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Julien Iguchi-Cartigny | 10 Feb 15:53 2015
Picon
Picon

[uml-user] start a xterm on con1 fails

Hello,

I'm maintaining Netkit-NG, a set of scripts to boot and configure small
networks using UML machines for teaching purposes.

<https://netkit-ng.github.io/>

This set of scripts is based on Netkit

<http://www.netkit.org/>

which was using kernel from Debian Lenny. Starting UML with con1=xterm
was working at this time. But now, using the same configuration to boot
Debian Wheezy UML kernel with a xterm on con1 fails.

So far I'm stuck with the following command lines.

This one works (starts a xterm with UML):

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/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=null SELINUX_INIT=0

But if I want to start UML with a second xterm on the con1, i.e.
replacing con1= null by con1=xterm in the commad line, no second xterm
is started. This was the expected behavior in the original netkit (and
it worked).

I'm looking for help, especially about how to debug this problem (so far
no error messages in messages or dmesg in the host or the UML machine)
and how port-helper works on this case.

I think UML cannot found xterm or port-helper, as if UML is started with
xterm on con0 and con1 it block after display the amount of physical
memory. The command line is:

/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/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=xterm con1=xterm

Thanks for your help.

Regards.

Julien

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[uml-user] Run 2.6 kernel on 2.4 host

Hi,

I need to run some recent software on a legacy server running 2.4.18 
kernel. Sadly it is not possible to rebuild the sotware to run natively 
with that kernel (our code requires boost, boost requires gcc 4.5+, 
gcc4.5+ doesn't like old glibc and recent glibc doesnt build for 2.4 
kernel).
So I'm trying to run UML 2.6 kernel on 2.4 system. I tried prebuilt 
2.6.27 kernel from (http://uml.devloop.org.uk/kernels.html) but it 
refused to run on 2.4 ("ERROR: kernel too old"). Next, I tried to build 
it on the Debian Woody VM with gcc 2.95 & 3.4 and glibc 2.2 but got 
dozens of errors.
Is it possible to build and run 2.6 on 2.4? What environment is 
required? What are the limitations if any?

Thank you!

--

-- 
Best regards,
Vladimir

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Gmane