IMFS on ram-disk

Ian Caddy ianc at
Tue Jul 24 09:19:02 UTC 2018

Hi Udit,

While I am not familiar with your exact setup, we had issues with larger 
files on the IMFS using RTEMS4.10.

We discovered that there is a default max size of an IMFS file which is 
around 4.3MBytes.

It can be changed by changing the bytes per block in the CONFDEFS:

/* IMFS file system block size increase to make max file size 
68,173,568, instead of 4,329,344  */

We performed this update to increase the maximum file size as shown above.

Hope this helps.


Ian Caddy

On 24/07/2018 4:48 PM, Udit agarwal wrote:
> Hi all,
> I've been trying to use IMFS with a ramdisk on BBB. Here's what i did:
> After creating a ram disk (block size:512, block count:262144), i used 
> mount_and_make_target_path("/dev/rda","/mnt",RTEMS_FILESYSTEM_TYPE_IMFS,RTEMS_FILESYSTEM_READ_WRITE,NULL)
> There is no error during bootup, but when allocating a file(in the 
> /mnt directory) of size 10MB(or even of 1MB) it gives a file too large 
> error.
> I've used similar config for RFS too and that did worked, so probably 
> there's no issue while setting up the RAM disk.
> I've also tried testsuite/fstests/imfs_support setup, but looks like 
> similar method doesn't work with ram-disks
> -- 
> Regards,
> Udit kumar agarwal
> _______________________________________________
> users mailing list
> users at

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