User Mode Linux

User Mode Linux

[Vishal Thanki]

Hi All,

I am trying to create a loopback block device under a UML (running
kernel 3.1.0).
I used following commands:

# dd if=/dev/zero of=/tmp/store1 bs=1024 seek=2047 count=1
# losetup /dev/loop1 /tmp/store1

But the 2nd command (i.e. losetup) returns with the error complaining
"/dev/loop1" is not present, but I can see /dev/loop[0..7] files
present.

My question, is it possible to do this exercise under UML (User mode linux)?

Thanks,
Vishal

User Mode Linux

[Lakshmipathi.G]

But the 2nd command (i.e. losetup) returns with the error complaining
"/dev/loop1" is not present, but I can see /dev/loop[0..7] files
present.

Try loading the module as -

#modprobe loop

and check again.

My question, is it possible to do this exercise under UML (User mode linux)?
If you are asking about whether is it possible use to loop device on UML
machine,
then the answer is 'Yes'.

HTH

-- 
----
Cheers,
Lakshmipathi.G
FOSS Programmer.
www.giis.co.in
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User Mode Linux

[Vishal Thanki]

On Tue, Nov 15, 2011 at 8:09 PM, Lakshmipathi.G
<lakshmipathi.g@gmail.com> wrote:
> But the 2nd command (i.e. losetup) returns with the error complaining
> "/dev/loop1" is not present, but I can see /dev/loop[0..7] files
> present.
>
> Try loading the module as -
>
> #modprobe loop

This worked. Thanks for pointing that out.

> and check again.
> My question, is it possible to do this exercise under UML (User mode linux)?
> If you are asking about whether is it possible use to loop device on UML
> machine,
> then the answer is 'Yes'.
> HTH
>
> --
> ----
> Cheers,
> Lakshmipathi.G
> FOSS Programmer.
> www.giis.co.in
>

User Mode Linux

[Vishal Thanki]

On Wed, Nov 16, 2011 at 9:14 AM, Vishal Thanki <vishalthanki@gmail.com> wrote:
>
> On Tue, Nov 15, 2011 at 8:09 PM, Lakshmipathi.G
> <lakshmipathi.g@gmail.com> wrote:
> > But the 2nd command (i.e. losetup) returns with the error complaining
> > "/dev/loop1" is not present, but I can see /dev/loop[0..7] files
> > present.
> >
> > Try loading the module as -
> >
> > #modprobe loop
>

I have one more question in the same line (i.e. related to UML). I
tried loading an external module (build for ARCH=um type). I am able
to load that module only if i've booted UML with following command:

./linux ubda=<raw_file_system_path>

If i pass the mem parameter, i.e.

./linux ubda=<raw_file_system_path> mem=512M

I am not able to load the module. The error that I am seeing is:

overflow in relocation type 11 val a121c3c0
`tun' likely not compiled with -mcmodel=kernel

I tried to load the tun.ko. This holds true for any manually built
simple hello_world kind of module too (where i added -mcmodel=kernel
parameter in Makefile).

What can be wrong with "mem=512M" parameter? I change the size of mem
to 128K to 1G, but nothing works. It just doesn't like "mem" parameter
as bootargs.


>
> This worked. Thanks for pointing that out.
>
> > and check again.
> > My question, is it possible to do this exercise under UML (User mode linux)?
> > If you are asking about whether is it possible use to loop device on UML
> > machine,
> > then the answer is 'Yes'.
> > HTH
> >
> > --
> > ----
> > Cheers,
> > Lakshmipathi.G
> > FOSS Programmer.
> > www.giis.co.in
> >

User Mode Linux

[Vishal Thanki]

On Thu, Nov 17, 2011 at 7:04 PM, Anuz Pratap Singh Tomar
<chambilkethakur@gmail.com> wrote:
>
>
> On Thu, Nov 17, 2011 at 12:04 PM, Vishal Thanki <vishalthanki@gmail.com>
> wrote:
>>
>> On Wed, Nov 16, 2011 at 9:14 AM, Vishal Thanki <vishalthanki@gmail.com>
>> wrote:
>> >
>> > On Tue, Nov 15, 2011 at 8:09 PM, Lakshmipathi.G
>> > <lakshmipathi.g@gmail.com> wrote:
>> > > But the 2nd command (i.e. losetup) returns with the error complaining
>> > > "/dev/loop1" is not present, but I can see /dev/loop[0..7] files
>> > > present.
>> > >
>> > > Try loading the module as -
>> > >
>> > > #modprobe loop
>> >
>>
>> I have one more question in the same line (i.e. related to UML). I
>> tried loading an external module (build for ARCH=um type). I am able
>> to load that module only if i've booted UML with following command:
>>
>> ./linux ubda=<raw_file_system_path>
>>
>> If i pass the mem parameter, i.e.
>>
>> ./linux ubda=<raw_file_system_path> mem=512M
>>
>> I am not able to load the module. The error that I am seeing is:
>>
>> overflow in relocation type 11 val a121c3c0
>> `tun' likely not compiled with -mcmodel=kernel
>>
>> I tried to load the tun.ko. This holds true for any manually built
>> simple hello_world kind of module too (where i added -mcmodel=kernel
>> parameter in Makefile).
>>
>> What can be wrong with "mem=512M" parameter? I change the size of mem
>> to 128K to 1G, but nothing works. It just doesn't like "mem" parameter
>> as bootargs.
>>
>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
> try compiling it statically

I gave tun.ko as an example. I want to load my own module which is not
part of linux kernel.

User Mode Linux

[Mulyadi Santosa]

On Thu, Nov 17, 2011 at 19:04, Vishal Thanki <vishalthanki@gmail.com> wrote:
> I have one more question in the same line (i.e. related to UML). I
> tried loading an external module (build for ARCH=um type). I am able
> to load that module only if i've booted UML with following command:
>
> ./linux ubda=<raw_file_system_path>
>
> If i pass the mem parameter, i.e.
>
> ./linux ubda=<raw_file_system_path> mem=512M
>
> I am not able to load the module. The error that I am seeing is:
>
> overflow in relocation type 11 val a121c3c0
> `tun' likely not compiled with -mcmodel=kernel

could be a UML specific bug. Have you tried other kernel version?

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com