Filesystem mounting/layout

[Sebastian Huber]

On 03/11/2013 11:48 AM, Matthew J Fletcher wrote:
> Hi,
>
> Looking in the fileio sample it looks pretty simple to register a IMFS device,
> but could i have some guidance on how best to setup an IMFS root, IMFS store on
> SRAM and a RFS store on NOR Flash.
>
> Is it possible/sensible to use an IMFS filesystem as both a root filesystem and
> also as storage filesystem as you would on linux ?

The IMFS uses currently a fixed allocator (malloc()) so it makes no sense to 
have more than one IMFS instances.  It would be possible to add instance 
specific allocators via a mount option, but this is not implemented.

>
> e.g IMFS would provide
>
> /etc
> /sram <- which is a 256k block
> /flash <- which is a mounted RFS 4M block of NOR
>
> Registering the IMFS device driver looks simple enough, but when it comes to
> mounting and formating both IMFS and RFS i am slightly confused.
>
> The RFS wiki entry shows using rtems_rtfs_format() and the standard mount()
> call with a rtems_filesystem_mount_table_entry structure. But the fileio sample
> shows using rtems_fsmount() passing in an fstab_t structure.
>
> Also is RFS support a configure time option that i need to have enable previously ?

You have to configure the available file systems, see

http://www.rtems.org/onlinedocs/doxygen/cpukit/html/group__FileSystemTypesAndMount.html#gaf3c1bed49bb0f3dec88d330b4f88d48b

For NOR flash support on RFS you need a block device driver for the NOR flash.  See

http://git.rtems.org/rtems/tree/cpukit/libblock/src/nvdisk.c

-- 
Sebastian Huber, embedded brains GmbH

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