Some additional information about this issue.

http://user-mode-linux.sourceforge.net/new/problems.html#vdso says to
disable CONFIG_COMPAT_VDSO on the host. According to Ingo Molnar
himself, disabling CONFIG_COMPAT_VDSO (http://lwn.net/Articles/184734/
) means that VDSO is not always at the usual 0xffffe000 address.  I
observe that my host does not place VDSO there:

[EMAIL PROTECTED] [911](~) > cat /proc/self/maps | grep vdso
006c1000-006c2000 r-xp 006c1000 00:00 0          [vdso]
[EMAIL PROTECTED] [912](~) > cat /proc/self/maps | grep vdso
00a46000-00a47000 r-xp 00a46000 00:00 0          [vdso]
[EMAIL PROTECTED] [913](~) > cat /proc/self/maps | grep vdso
00196000-00197000 r-xp 00196000 00:00 0          [vdso]
[EMAIL PROTECTED] [914](~) > cat /proc/self/maps | grep vdso
007e0000-007e1000 r-xp 007e0000 00:00 0          [vdso]

This seems to imply that CONFIG_COMPAT_VDSO is already disabled on
this host, and that the vdso location is subject to full
randomization. As such, if I understand the UML website correctly, the
suggested fix is already applied.

In addition, I want to point out that the UML kernel also hangs when
statically linked.

 - Godmar

On 9/5/07, Godmar Back <[EMAIL PROTECTED]> wrote:
> I'm using a stock 2.6.22.5 distribution kernel for UML. I'm
> experiencing the problem described here:
> http://user-mode-linux.sourceforge.net/new/problems.html#vdso where
> the UML kernel hangs.
>
> The host is a FC6 machine with glibc-common-2.5-10.fc6 and a
> 2.6.20-1.2962.fc6 kernel. The problem showed up after adding a few
> lines of code to my UML kernel; these lines aren't exercised during
> the boot process, however. It appears that simply adding those lines
> makes the problem appear and removing them makes it go away.
>
> The suggestion given at the URL above include changing the kernel
> configuration of the host (if I understand them correctly). Since I do
> not have root access (these are shared university lab machines), I do
> not have the option of installing my own host kernel.
>
> Is there a way to avoid this issue?  I'm planning on using UML for a
> student assignment, however, I would be very hesitant to do so if this
> problem persists since it would make development impossible.
>
> Thanks.
>
>  - Godmar
>

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