[uClinux-dev] Minimum size of uCLinux and J9 compatibility

Jamie Lokier jamie at shareable.org
Sun Feb 1 06:59:00 EST 2009

Jonathan Wong wrote:
> I won't need a web browser, just a thin client to communicate with a 
> central server.

You can write a client in any language.  Java seems a bit heavy and
hard to get going, if you don't specifically need Java on it.

> I was just told our device doesn't have RAM at all, only 8MB ROM. Is that 
> possible?

It'll have RAM, the EM8623 needs it.  It's internal cache isn't big
enough to run Linux. :-) 128MB RAM is the maximum it can use, without
special hacks, and that's probably how much you've got, because 64MB
is too small for H.264 support and Linux at the same time.

> All these EABI/OABI stuff seems complicated. I have to compile different 
> parts of my application with different compilers?

No, you can just use the compiler distributed by Sigma Designs if you
like, it's not a bad compiler, just old.

Sigma's EM8623 SDK is based on very old tools: GCC 2.95.3 and Linux
2.4.26-uc0, which are both ancient (about 5 years old).  Also uClibc
0.9.26 and Busybox 1.00, again rather old.

That's fine, as long as you stay with old software from 5 years ago

Some new things you might want to use (you did mention J9!) might not
compile with GCC 2.95.3; then you have some fun.  But mostly, things
work, it's not a bad compiler.  Just old.  It does have a few ARM bugs.

If you find you need to use a new compiler, then you have to be
careful about compatibility issues linking to Sigma's SDK binary
libraries.  If it was all open source there would be no problem, we'd
recompile everything with current tools, but because it's closed that
needs Sigma's cooperation.

My solution is to use Sigma's GCC 2.95.3 when building a program that
links to their libraries, but use newer GCC for other programs (that
don't use Sigma's libraries at all).

-- Jamie

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