Ubi2- using NandSim for simulating flash and mounting ubi.

Ubi2- using NandSim for simulating flash and mounting ubi.

[Shweta Shetty]

Hi,

To test ubi2 we intend to use NANDSIM. However we are facing certain problems.

>From what we have understood, the method of using NANDSIM is :
1>create an empty flash device (By default this uses the ram memory
but we can allocate other by the cache_file option)
2>mount ubi on it
3>mount ubifs on it
=> (Here we can load the previously stored image)
4>use it
5>while unmounting save the image on permanant storage

So as we can see, though NANDSIM can be effectively used for
simulating flash , it is of limited use in our project for testing
mount time as every time only the empty device is mounted.

>From the ubi code that we have now studied , there is a flag set for
an empty device and in such case , all the system does is that it
initialises all its data structures.Hence we cannot show the
performance of our project on NANDSIM.

Our we missing some crucial point?
We would be grateful for clarification.


-- 
Shweta Shetty
http://shweta-kaleidoscope.blogspot.com/
Humility is a strange thing. The minute you know you have got it you
have lost it.

Re: Ubi2- using NandSim for simulating flash and mounting ubi.

[Artem Bityutskiy]

Hi,

sorry, I am not sure understand the question.

On Fri, 2010-01-08 at 16:46 +0530, Shweta Shetty wrote:
> Hi,
> 
> To test ubi2 we intend to use NANDSIM. However we are facing certain problems.
> 
> From what we have understood, the method of using NANDSIM is :
> 1>create an empty flash device (By default this uses the ram memory
> but we can allocate other by the cache_file option)
> 2>mount ubi on it
> 3>mount ubifs on it
> => (Here we can load the previously stored image)

If you want to write some pre-created image (e.g., created with
mkfs.ubifs/ubinize) or previously saved image (e.g., you dumped
your /dev/mtdX to a file previously), then you have to do this _before_
attaching the MTD device to UBI. IOW, you have to do this between steps
1 and 2.

> 4>use it
> 5>while unmounting save the image on permanant storage

After you have unmounted everything, you can save it, yes.

> So as we can see, though NANDSIM can be effectively used for
> simulating flash , it is of limited use in our project for testing
> mount time as every time only the empty device is mounted.

No. You can write your contents there before mounting.

> From the ubi code that we have now studied , there is a flag set for
> an empty device and in such case , all the system does is that it
> initialises all its data structures.

It does this _only_ if you feed it an empty flash. Do not feed it an
empty flash, feed it a formatted flash, then it will not initialize it.

> Hence we cannot show the
> performance of our project on NANDSIM.

Well, of course in any case, performance is better shown on a real
device.

> Our we missing some crucial point?
> We would be grateful for clarification.

Not sure I clarified, because I did not really understand the question,
but HTH.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

Re: Ubi2- using NandSim for simulating flash and mounting ubi.

[Shweta Shetty]

Hi ,
Thank you for your help.
We had not tried the "ubinize" utility and hence were not able to
mount ubi with the saved data.
Having followed your instructions , we tried it and it works perfectly fine now.
Thank you again !

On Sun, Jan 17, 2010 at 2:44 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
>
> Hi,
>
> sorry, I am not sure understand the question.
>
> On Fri, 2010-01-08 at 16:46 +0530, Shweta Shetty wrote:
> > Hi,
> >
> > To test ubi2 we intend to use NANDSIM. However we are facing certain problems.
> >
> > From what we have understood, the method of using NANDSIM is :
> > 1>create an empty flash device (By default this uses the ram memory
> > but we can allocate other by the cache_file option)
> > 2>mount ubi on it
> > 3>mount ubifs on it
> > => (Here we can load the previously stored image)
>
> If you want to write some pre-created image (e.g., created with
> mkfs.ubifs/ubinize) or previously saved image (e.g., you dumped
> your /dev/mtdX to a file previously), then you have to do this _before_
> attaching the MTD device to UBI. IOW, you have to do this between steps
> 1 and 2.
>
> > 4>use it
> > 5>while unmounting save the image on permanant storage
>
> After you have unmounted everything, you can save it, yes.
>
> > So as we can see, though NANDSIM can be effectively used for
> > simulating flash , it is of limited use in our project for testing
> > mount time as every time only the empty device is mounted.
>
> No. You can write your contents there before mounting.
>
> > From the ubi code that we have now studied , there is a flag set for
> > an empty device and in such case , all the system does is that it
> > initialises all its data structures.
>
> It does this _only_ if you feed it an empty flash. Do not feed it an
> empty flash, feed it a formatted flash, then it will not initialize it.
>
> > Hence we cannot show the
> > performance of our project on NANDSIM.
>
> Well, of course in any case, performance is better shown on a real
> device.
>
> > Our we missing some crucial point?
> > We would be grateful for clarification.
>
> Not sure I clarified, because I did not really understand the question,
> but HTH.
>
> --
> Best Regards,
> Artem Bityutskiy (Артём Битюцкий)
>



--
Shweta Shetty
http://shweta-kaleidoscope.blogspot.com/
Humility is a strange thing. The minute you know you have got it you
have lost it.