[Netkit.users] unable to create a vm (kernel panic)

[Massimo Rimondini]

Hi Iuz.

The problem you are reporting does not seem to be related to the use of 
SKAS mechanisms. SKAS support is checked for much before the instant in 
which the panic occurs (the output you have pasted does not show that - 
probably because you were using the no-skas kernel - but the check is 
performed just before the line "Checking PROT_EXEC mmap in /tmp...OK").

Instead, I think it's related to an unexpected interaction between the 
UML kernel and some patch the SUSE kernel has been compiled with.

Other users have been reporting a similar problem (see 
http://www.mail-archive.com/user-mode-linux-user@lists.sourceforge.net/msg00951.html), 
which may be caused by a buggy SYSEMU patch applied to the SUSE 9.2 
kernel 
(http://www.mail-archive.com/user-mode-linux-user@lists.sourceforge.net/msg00952.html).

Until a more recent Netkit kernel is made available, I think the best 
way to go is to perform an upgrade of either your SUSE installation 
(there have been reports of things starting to work again with SUSE 9.3 
- see 
http://www.mail-archive.com/user-mode-linux-user@lists.sourceforge.net/msg00994.html), 
or simply of your host kernel 
(http://www.mail-archive.com/user-mode-linux-user@lists.sourceforge.net/msg00979.html), 
the latter solution being the most advisable.

Hope this helps.

Regards,
Massimo Rimondini.

iuz zui wrote:

>hi all,
>i'm new to netkit and unlucky, i'm unable to solve a
>problem that occur when 
>i try to create a new vm on a Suse 9.2.
>i've tried all the two kernel (with and without skas)
>without benefits.
>below i quote some useful lines for understand what
>the problem is, in which, 
>as you will see there is a really-not-so-much
>sympathetic Kernel panic.
>
>[quoting "linux:~ # vstart pc1 --eth0=0 --verbose
>--new"]
>Virtual machine will create pc1.disk on the basis of
>/root/Desktop/netkit/netkit
>-1.4.2/fs/default.
>starting hub...
>uml_switch -hub -unix /tmp/uml/vhub_0_0.cnct
>
>>/dev/null &
>>
>starting virtual machine...
> /root/Desktop/netkit/netkit-1.4.2/kernel/linux
>ubd0=pc1.disk,/root/Desktop/netk
>it/netkit-1.4.2/fs/default root=98:1 name=pc1
>title=pc1 hosthome=/root mem=16M u
>ml_dir=/tmp/uml eth0=daemon,,,/tmp/uml/vhub_0_0.cnct
>con= con0=xterm
>linux:~ # Checking PROT_EXEC mmap in /tmp...OK
>tracing thread pid = 6501
>Linux version 2.6.8.1-1um (max a pantera) (gcc version
>3.3.3 20040412 (Red Hat Lin
>ux 3.3.3-7)) #1 Wed Oct 27 10:00:40 CEST 2004
>Built 1 zonelists
>Kernel command line:
>ubd0=pc1.disk,/root/Desktop/netkit/netkit-1.4.2/fs/default
>root=98:1 name=pc1 title=pc1 hosthome=/root mem=16M
>uml_dir=/tmp/uml eth0=daemon
>,,,/tmp/uml/vhub_0_0.cnct con= con0=xterm
>PID hash table entries: 16 (order 4: 128 bytes)
>Dentry cache hash table entries: 4096 (order: 2, 16384
>bytes)
>Inode-cache hash table entries: 2048 (order: 1, 8192
>bytes)
>Memory: 12976k available
>Calibrating delay loop... 1933.31 BogoMIPS
>Mount-cache hash table entries: 512 (order: 0, 4096
>bytes)
>Checking for host processor cmov support...Yes
>Checking for host processor xmm support...No
>Checking that ptrace can change system call
>numbers...OK
>Checking syscall emulation patch for
>ptrace...<0>Kernel panic: check_ptrace : ch
>ild exited with status 0x100
>In idle task - not syncing
> <6>SysRq : Show Regs
>
>Kernel panic: Segfault with no mm
>In idle task - not syncing
> <6>SysRq : Show Regs
>
>EIP: 0073:[<a0024f72>] CPU: 0 Not tainted ESP:
>007b:a01ebe80 EFLAGS: 00210292
>    Not tainted
>EAX: 00000000 EBX: a01f7f34 ECX: a01ba3c3 EDX:
>a01ecff8
>ESI: 00000070 EDI: 00000000 EBP: a01ecff8 DS: 007b ES:
>007b
>Call Trace: [<a00c1f74>] [<a0016e76>] [<a00359de>]
>[<a002aa72>] [<a0016511>]
>   [<a0031f76>] [<a0032331>] [<a016aef7>] [<a0014c7b>]
>[<a00167f6>] [<a0024f72>]
>   [<a0014cc2>] [<a00199b5>] [<a0019a1d>] [<a0016819>]
>[<a016ac18>] [<a0024f72>]
>   [<a002b40d>] [<a00c1fd3>] [<a00c1f74>] [<a0016e76>]
>[<a00359de>] [<a002aa72>]
>   [<a0012bd6>] [<a01a9989>] [<a00191b0>] [<a00041cd>]
>[<a0002596>] [<a00191b0>]
>   [<a00191b0>] [<a0002554>] [<a0018472>] [<a0019238>]
>[<a0016808>] [<a0181d6a>]
>   [<a0018440>]
>[/quoting "linux:~ # vstart pc1 --eth0=0 --verbose --new"]
>
>  
>
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