External RAM filesystem

[Thomas Doerfler]

Hi,

Aitor.Viana.Sanchez at esa.int schrieb:
> 
> Hi,
> 
> OK the problem eventually was only half mine ;). I'll try to explain.
> 
>        
>         #define _FILESYSTEM_SIZE                        (0x1000000)    
>    // 16MB
>         static unsigned int numberOfBlocks = (_FILESYSTEM_SIZE / 512);
> 
> The problem is that, with this numberOfBlocks  value, RTEMS is not able
> to mount the filesystem, raising an error. The error shows up when
> msdos_format() is called, returning "not such file or directory". On the
> contrary, if numberOfBlocks = 40 (for instance) everything goes well.
> 
> Is there any limitation within RTEMS w.r.t. the size of the filesystem?

Hm, this is strange. We are currently working with Compact Flash cards
with about 2GByte of capacity, and there are no such problems. We are
also formatting them with msdos_format().

There MIGHT be a problem with the ramdisk driver.

Normally you would not want to use a MSDOS-based ramdisk in RTEMS,
because you can also use the "IMFS" (in-memory-file system) which uses
the heap to get the memory it needs.

The ramdisk driver was a test vehicle to implement the DOS filesystem
and, AFAIK, was not/seldomly used with the capacity you mentioned.

Can you see "/dev/ramdisk0" in the device tree of the (in memory) file
system?

wkr,
Thomas.


> 
> thanks in advanced.
> 
> //avs
> 
> -----------------------------
> Aitor Viana Sánchez
> 
> ESA - European Space Technology Centre (ESTEC)
> TEC-EDD - Computer and Data Systems Section
> ESA/ESTEC P.O. Box 299 / 2200AG Noordwijk ZH, The Netherlands
> Tel (+31) 71 565 6727
> Email: aitor.viana.sanchez at esa.int
> 
> 
> *Thomas Doerfler <Thomas.Doerfler at embedded-brains.de>*
> Sent by: rtems-users-bounces at rtems.org
> 
> 11/15/2007 09:54 PM
> 
> 	
> To
> 	Aitor.Viana.Sanchez at esa.int
> cc
> 	rtems-users at rtems.org
> Subject
> 	Re: External RAM filesystem
> 
> 
> 	
> 
> 
> 
> 
> Hi,
> 
> Aitor.Viana.Sanchez at esa.int schrieb:
>>
>> Hi,
>>
>> I got everything ready to send an example and to include a wiki entry
>> but fist...the example is only working in rtems-4.7.99.2-1.0.3. I also
>> tried with RTEMS 4.6.5 but looks like some functions are not implemented
>> in this version. This is the compilation output.
> 
> ys you are right, I implemented the msdos_format function somewhere
> after 4.6.5, so you might have missed it in that version.
> 
> See:
> 
> http://www.rtems.com/cgi-bin/cvsweb.cgi/rtems/cpukit/libfs/src/dosfs/msdos_format.c
> 
> The module should be back-portable if required, but there might be some
> other unresolved references then.
> 
> Are you currently stuck to 4.6.5 in your work? Which architecture are
> you working on?
> 
> wkr,
> Thomas.
> 
> --
> --------------------------------------------
> Embedded Brains GmbH
> Thomas Doerfler           Obere Lagerstr. 30
> D-82178 Puchheim          Germany
> email: Thomas.Doerfler at embedded-brains.de
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