[uClinux-dev] Adding new board support [& other questions]

Bruce Paterson bruce at tele-ip.com
Sun Nov 18 21:38:04 EST 2001


Tom Walsh wrote:
> 
> First of all, let me apologize for the tone of the reply, you deserved
> more respect.  I was having a bad day and really should have been more
> carefull in the wording.

Apology accepted -:)
 
> of time in collecting together information about uClinux.  His site is
> at: http://uClinux.home.at

I've been there. Someone mentioned on the list recently and thats how I
found
it. Someone also said it shoudl be pointed to by the official site.
Can't agree
more.
Unfortunately it didn't have much in the way of application
decriptions/comparisons
which is what I'm after. 
Greg suggested I google on each one, and at the very least I will put
together
all the bookmarks I find useful and throw that in a document for the
site.
No doubt it will experience link rot quickly, but it'll be a start.
It may be hard to make comparisons still though, since developers tend
to be
quite upbeat about their own creations of course (ever read all the
comments in
a standard distribution install ?).

> The current distro, done by Greg Ungerer, is a quantum leap above what
> we had been working with before.  The distro is well put together of
> apps, and kernels (2.0 & 2.4) that work together.  Before Greg started
> issuing these distros, we had a hodge-podge of libraries and apps that
> were problematic to use.

Yes. I tried the to compile the latest CVS 2.4 uClibc and 2.4 kernel and
ran
into all sorts of errors, but Greg's distro seems much cleaner.
 
> Porting to a new platform is not documented (AFAIK), but is relatively
> easy.  One of the first platforms to use uClinux was the uCsimm.  When I

Actually I'm already past that stage. I have 2.0.31 running fine on my
target
with some pre-packaged apps from the original 68360 release. I actually
did
exactly the "find" you suggested to find all the files I had to mod.
I've
since mod-ed all the similar files in Gregs 2.4 release prior to
attempting
the make, and made my own vendor tree entry.

> ported uClinux to my M68EZ328 platform, I simply did a:
> 
> find . -type f | xargs fgrep -l CONFIG_UCSIMM
> 
> in the root of the uClinux kernel source tree.  This gave me a list of
> files to consider as to what changes I had to make for my platform (then
> the CONFIG_EZ328SIMM).  I then edited the files, found the conditionals
> for UCSIMM and added my own conditionals as needed.  The crt0.S (system
> kernel startup) is the one file you will have to write to match your
> platform (hardware initialization, placing the .bss, .text, and .data
> sections into their proper place in RAM).  The adjustments / additions
> made to the kernel source are  relatively minor and is just to map your
> RAM to the kernel resources (memory management and romfs location).

Make the above paragraph a starting point for a document about porting
and
submit it to the website.
 
> > > > It would certainly help if every module had a footprint size (rom & ram)
> > > > and an
> > > > indicator of functionality (maybe peg standard linux distribution
> > > > versions as 100%)

I can see the problem with different platforms/memory options changing
the size
of the code. It's probably rare, though, that application
implementations
will "swap" positions in a size comparison when moving architectures. 
Possibly a size as compiled for an Intel PC might at least provide a
common
basis for comparisons. I agree it's a bastard to have to do this though.

At the end of the day everyone has to make these choices, be it by size,
functions
required, reliability or rumour. 
Anyone suggest a better way ?

Cheers,
Bruce
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