DOC2000 and Kernel 2.3 ??

DOC2000 and Kernel 2.3 ??

[Udi Finkelstein]

Hi,

I'm new to this list (and to DiskOnChip 2000 in general).

I have an embedded linux system running with a 2.0.x based kernel and m-sys's
drivers.

I want to build a new 2.3 kernel based system with the following structure:

* /boot partition with a 2.3 Kernel containing
  a ramdisk based root file system (initrd).
* RAM disk contains a skeleton filesystem with
  99% of the files pointing to a CRAMFS (the
  2.3.x compressed ROM filesystem) based partition
  in the doc2000.
* Data is stored on a 3rd partition (e2fs ??).

Advantages:
1. All fixed data is compressed (kernel is compressed by nature, initrd
compressed by gzip, CRAMFS compressed by design).
2. RAM based root filesystem allows modifying anything in the system without
writing to the doc2000, preventing any corruption. Rebooting the system
returns it to a clean state.
3. Separate data partition is separate from the rest of the system and can be
easily reformatted without affecting system.

Now the big Question: What is the best (any) way to get a doc2000 working with
the 2.3 kernel?

I see 3 possible options:

1. Hacking the original m-sys 2.2.x driver to work under 2.3.x. Is this
possible? How much of the binary only portion depends on the 2.2.x kernel API?
Can it be adapted to 2.3.x by changing only the skeleton code around it?

2. Using the Axis JFFS code. Is it stable? does it work at all?

3. using the MTD FFS code. Does it finally work under 2.3.x?

thanks,
Udi


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Re: DOC2000 and Kernel 2.3 ??

[Stuart Lynne]

In article <f1c7fssr0pi4tvjhv4g10trhkqq28j0i6r@4ax.com>,
Udi Finkelstein <udif@bigfoot.com> wrote:
>Hi,
>
>I'm new to this list (and to DiskOnChip 2000 in general).
>
>I have an embedded linux system running with a 2.0.x based kernel and =
>m-sys's
>drivers.
>
>I want to build a new 2.3 kernel based system with the following =
>structure:
>
>* /boot partition with a 2.3 Kernel containing
>  a ramdisk based root file system (initrd).
>* RAM disk contains a skeleton filesystem with
>  99% of the files pointing to a CRAMFS (the
>  2.3.x compressed ROM filesystem) based partition
>  in the doc2000.
>* Data is stored on a 3rd partition (e2fs ??).
>
>Advantages:
>1. All fixed data is compressed (kernel is compressed by nature, initrd
>compressed by gzip, CRAMFS compressed by design).
>2. RAM based root filesystem allows modifying anything in the system =
>without
>writing to the doc2000, preventing any corruption. Rebooting the system
>returns it to a clean state.
>3. Separate data partition is separate from the rest of the system and =
>can be
>easily reformatted without affecting system.
>
>Now the big Question: What is the best (any) way to get a doc2000 working=
> with
>the 2.3 kernel?
>
>I see 3 possible options:
>
>1. Hacking the original m-sys 2.2.x driver to work under 2.3.x. Is this
>possible? How much of the binary only portion depends on the 2.2.x kernel=
> API?
>Can it be adapted to 2.3.x by changing only the skeleton code around it?

Very little if any. You should be able to just modify the fldrvlnx.c file
appropriately and have it work.

I'm not to sure what CRAMFS is going to do for you. It's not too hard
to have a minimal system entirely on the RAM disk.


-- 
Stuart Lynne <sl@fireplug.net>                __O 
<http://www.thinlinux.org>                  _-\<,_               604-461-7532
PGP Fingerprint: 28 E2 A0 15 99 62 9A 00   (_)/ (_)   88 EC A3 EE 2D 1C 15 68


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Re: DOC2000 and Kernel 2.3 ??

[Udi Finkelstein]

Stuart Lynne wrote:
> 
> In article <f1c7fssr0pi4tvjhv4g10trhkqq28j0i6r@4ax.com>,
> Udi Finkelstein <udif@bigfoot.com> wrote:
> 
> >I see 3 possible options:
> >
> >1. Hacking the original m-sys 2.2.x driver to work under 2.3.x. Is this
> >possible? How much of the binary only portion depends on the 2.2.x kernel=
> > API?
> >Can it be adapted to 2.3.x by changing only the skeleton code around it?
> 
> Very little if any. You should be able to just modify the fldrvlnx.c file
> appropriately and have it work.
> 
> I'm not to sure what CRAMFS is going to do for you. It's not too hard
> to have a minimal system entirely on the RAM disk
If I want to use a filesystem containing read-only files (executables 
and data files) which is 2 MB for example, I would require either:
*  2MB  conventional filesystem (e2fs) mounted read-only, using no 
dedicated RAM (other than caching/buffering), but using 2MB of the flash 
disk (50% in my case).
* compressed RAM disk mounted as an initrd, using 2MB RAM (out of the 
8MB DRAM I have), but only 1MB flash (25% of the DOC2000-4MB I use, 
assuming 50% compression ratio).
* CRAMFS based partition using 1MB flash and no RAM.

Ofcourse, the bigger the partition needs to be, the higher the gains.

I'd rather have the 3rd option.

Also, where do I find a *complete* list of 2.2 -> 2.3 kernel changes? 
the only list I found was:

http://www.atnf.csiro.au/~rgooch/linux/docs/porting-to-2.3.html

and it is certainly lacking.

> Stuart Lynne <sl@fireplug.net>                __O 
> 
Udi



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Re: DOC2000 and Kernel 2.3 ??

[David Woodhouse]

udif@bigfoot.com said:
>  Now the big Question: What is the best (any) way to get a doc2000
> working with the 2.3 kernel?

> I see 3 possible options:

> 1. Hacking the original m-sys 2.2.x driver to work under 2.3.x. Is
> this possible? How much of the binary only portion depends on the
> 2.2.x kernel API? Can it be adapted to 2.3.x by changing only the
> skeleton code around it?

That could possibly work, with a bit of hacking.

> 2. Using the Axis JFFS code. Is it stable? does it work at all?

It's not clear yet whether it would work on NAND flash. 

> 3. using the MTD FFS code. Does it finally work under 2.3.x? 

I'm developing primarily under 2.3 - but my write support for NFTL still 
isn't reliable enough for production use.

In order of preference, I'd say you should go for 2,3,1 - and you're 
welcome to help with the code for any of them.

--
dwmw2




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Re: DOC2000 and Kernel 2.3 ??

[Finn Hakansson]

On Wed, 12 Apr 2000, David Woodhouse wrote:

> > 2. Using the Axis JFFS code. Is it stable? does it work at all?
> 
> It's not clear yet whether it would work on NAND flash. 

Yes, JFFS works and it is also stable. It is used in a couple of
our products (all our new Linux based products). However, as David
stated, where's only support for NOR flashes at the moment. In
the future, we or someone else, could add NAND flash support.

/Finn



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