IDE-Harddiskdriver for MCUs
Fri Jun 4 12:47:00 GMT 1999
How does one get access to the current RTEMS development tree?
----- Original Message -----
Sent: Friday, June 04, 1999 10:12 AM
Subject: Re: IDE-Harddiskdriver for MCUs
> On Fri, 4 Jun 1999, Kai Schaeffer wrote:
> > in a project I plan to connect a Flash memory card to a microcontroler
> > (68376). The Flash-card have an IDE-connector and it seems to me it is
> > very difficult to connect it to a MCU. It is also not a big problem to
> > write a software which read/write some sectors from the Flashcards (or
> > Harddisk!). It is an other thing to implement a filesystem. But I think
> > there exists the following:
> > 1. The glibc for my MCU with everything I need execpt the low level
> > 2. The source code of Linux with well implemented VFAT/FAT-Driver.
> > So the question is, if it is possible to adapt the Linux-drivers to use
> > them in an embedded application. I am sure it is very usefull for many
> > people to have a real harddisk/filesystem in there embedded systems.
> Anything is possible given enough time and money. :)
> Seriously, you would need to provide an adaption layer to glue the Linux
> code to whatever RTOS structure you end up with. It would be a more
> profitable investment of effort to provide the glue that would let
> multiple Linux filesystems and device drivers work largely unchanged than
> to hack working code mercilessly to fit it into your system. Plus leaving
> the original code intact as much as possible eases merging future
> upgrades to the original source.
> Another issue to consider is the memory requirements of the code you are
> moving. On any embedded system, you have memory constrants that were
> probably not a design consideration on the code you are moving from UNIX.
> > So the first question is, if there is already a solution for this
> > problem?! If not, the other questions are:
> > 1. Are there other persons who thinks it is interesting and usefull?
> Since we implemented much of this for RTEMS, I would have to say yes.
> > 2. Are there other persons who can help to realize this idea?
> FWIW the current RTEMS development tree has all the infrastructure to plug
> filesystems into. We have currently only implemented two filesystems: an
> "In-Memory File System" (IMFS) which is totally in RAM and a TFTP
> filesystem which is a filesystem interface to a TFTP client.
> To implement a non-volatile filesystem, you would need the Flash or disk
> device driver and the filesystem manager that organizes the blocks.
> This avoids more effort than you think. There is a significant amount of
> work to implement all the system calls that a C library requires and to
> implement the filesystem infrastructure to get mounts.
> Does this sound like it is going where you are thinking of?
> Joel Sherrill, Ph.D. Director of Research & Development
> joel@OARcorp.com On-Line Applications Research
> Ask me about RTEMS: a free RTOS Huntsville AL 35805
> Support Available (256) 722-9985
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