[Netkit.users] netkit2 on backtrack2final

[Massimo Rimondini]

Dear Arjuna,

this kind of error is due to the fact that the BackTrack2 kernel is 
configured without the VDSO compatibility flag set (I have just checked 
this).
A VDSO (Virtual Dynamic Shared Object) is a shared binary that the host 
kernel exposes in the address space of each running process, and that 
does not correspond to any physical .so file. This object supplies a 
process with functions that constitute an interface between user and 
kernel space, and that are used to implement system calls in the most 
efficient way depending on your host CPU.
In recent host kernels the mapping of the VDSO is randomized for 
security reasons. Unfortunately, this does not interplay properly with 
the current version of the Netkit kernel and libraries, as it looks for 
VDSO at a fixed address but is unable to find it. The VDSO compatibility 
flag in the host kernel ensures that the VDSO is also made available at 
a fixed address, but can only be enabled at compile time.

Therefore, the only appliable workaround to get Netkit working into 
BackTrack2 is to disable VDSO completely, which however results in a 
significant performance slowdown, as user space processes switch to a 
slower implementation of the system calls. You can achieve this in two ways:
1) at boot time, by typing the following at the "boot:" prompt of ISOLINUX:
/boot/vmlinuz vga=0x317 max_loop=255 initrd=/boot/initrd.gz init=linuxrc 
load_ramdisk=1 prompt_ramdisk=0 ramdisk_size=4444 root=/dev/ram0 rw vdso=0
2) when BackTrack2 is operational, by using the following command:
sysctl -w vm.vdso_enabled=0

Regards,
Massimo.

Arjuna Scagnetto wrote:
> i've made some better debugging and i get this error trying vstart pc1
>
> Inconsistency detected by ld.so: rtld.c: 1192: dl_main: Assertion 
> `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
> Kernel panic - not syncing: Attempted to kill init!
>  
> EIP: 0073:[<400114af>] CPU: 0 Not tainted ESP: 007b:9ffffa90 EFLAGS: 
> 00200246
>     Not tainted
> EAX: ffffffda EBX: 0000007f ECX: 9ffff820 EDX: 0000000a
> ESI: 00000000 EDI: b7f8d034 EBP: 9ffffab4 DS: 007b ES: 007b
> Call Trace:
> a082bb5c:  [<a0049fbd>] notifier_call_chain+0x2d/0x50
> a082bb6c:  [<a0118576>] bust_spinlocks+0x46/0x50
> a082bb7c:  [<a0037a01>] panic+0x71/0x120
> a082bb9c:  [<a003a8d3>] do_exit+0x1c3/0x370
> a082bbbc:  [<a0079c78>] vfs_writev+0x58/0x70
> a082bbec:  [<a003ab11>] do_group_exit+0x51/0x100
> a082bc1c:  [<a001c1a7>] execute_syscall_tt+0xe7/0x130
> a082bc8c:  [<a0017fb9>] record_syscall_start+0x59/0x70
> a082bcac:  [<a001c23e>] syscall_handler_tt+0x4e/0x90
> a082bccc:  [<a001d73d>] sig_handler_common_tt+0x8d/0x110
> a082bcdc:  [<a001b66b>] new_thread_handler+0x15b/0x190
> a082bce0:  [<a00111e0>] init+0x0/0x110
> a082bd0c:  [<a002e011>] sig_handler+0x21/0x40
> a082bd1c:  [<a01e3cb8>] __restore+0x0/0x8
>
> any help welcome
> Arjuna
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