[ECOS] Linux or ecos?

[ECOS] Linux or ecos?

[Roland Caßebohm]

Hi,

I want to develop an application that should run on different target
(i386, arm, mips).
The application itself is very simple and only needs access to serial
devices and to ethernet (with TCP/IP).
First I thought about using Linux as OS, but it should be used as
minimum RAM and FLASH as possible. The target hardware should have a
maximum of 1 MB RAM and 0,5 MB FLASH, so I have to shrink Linux more
then "make menuconfig" can do.
Here is my question, should I use ecos instead of Linux? How much RAM an
FLASH is needed For such a simple application, when using ecos.


Thanks
	Roland

Re: [ECOS] Linux or ecos?

[Andrew Lunn]

On Wed, Nov 14, 2001 at 01:37:02PM +0100, Roland Ca?ebohm wrote:
> I want to develop an application that should run on different target
> (i386, arm, mips).
> The application itself is very simple and only needs access to serial
> devices and to ethernet (with TCP/IP).
> First I thought about using Linux as OS, but it should be used as
> minimum RAM and FLASH as possible. The target hardware should have a
> maximum of 1 MB RAM and 0,5 MB FLASH, so I have to shrink Linux more
> then "make menuconfig" can do.

The TCP/IP stack can eat of lot of DRAM. How fast a network link do
you need. You can trade off speed for network buffer speed.

The ethernet device you use will also have a big affect. eg the i82559
uses 1Mbyte of RAM for its PCI window. I don't expect you will use
this device because its expensive and requires a PCI bridge etc. A
simpler, slower device with polled IO will require less memory, but
perform much slower.

If you application is really simple, you could think about building it
into redboot itself. That has its own really simple IP stack and basic
drivers for the serial ports.

        Andrew

Re: [ECOS] Linux or ecos?

[Roland Caßebohm]

Andrew Lunn wrote:
> 
> The TCP/IP stack can eat of lot of DRAM. How fast a network link do
> you need. You can trade off speed for network buffer speed.
> 
> The ethernet device you use will also have a big affect. eg the i82559
> uses 1Mbyte of RAM for its PCI window. I don't expect you will use
> this device because its expensive and requires a PCI bridge etc. A
> simpler, slower device with polled IO will require less memory, but
> perform much slower.
> 
> If you application is really simple, you could think about building it
> into redboot itself. That has its own really simple IP stack and basic
> drivers for the serial ports.
> 
>         Andrew

The i386 hardware have an ne2000 compatible chip on it and the arm and
mips hardware I down't by now. I think it will be onchip.
There is another idea I think of, I want to write source of my
application POSIX compatible because in future the application will be
more complex, so that I have to use Linux then. But in the release of
ecos which I have downloaded (1.3.1) I haven't seen POSIX funktions. 
I have read the documentation of building redboot. Is it right that
redboot is a simple ecos with a simple application?

Re: [ECOS] Linux or ecos?

[Gary Thomas]

On Thu, 2001-11-15 at 01:59, Roland Caßebohm wrote:
> Andrew Lunn wrote:
> > 
> > The TCP/IP stack can eat of lot of DRAM. How fast a network link do
> > you need. You can trade off speed for network buffer speed.
> > 
> > The ethernet device you use will also have a big affect. eg the i82559
> > uses 1Mbyte of RAM for its PCI window. I don't expect you will use
> > this device because its expensive and requires a PCI bridge etc. A
> > simpler, slower device with polled IO will require less memory, but
> > perform much slower.
> > 
> > If you application is really simple, you could think about building it
> > into redboot itself. That has its own really simple IP stack and basic
> > drivers for the serial ports.
> > 
> >         Andrew
> 
> The i386 hardware have an ne2000 compatible chip on it and the arm and
> mips hardware I down't by now. I think it will be onchip.
> There is another idea I think of, I want to write source of my
> application POSIX compatible because in future the application will be
> more complex, so that I have to use Linux then. But in the release of
> ecos which I have downloaded (1.3.1) I haven't seen POSIX funktions. 

You need to get the anonymous CVS version of eCos to get the POSIX 
functionality.  Indeed, you'll need anonCVS to get RedBoot as well.

> I have read the documentation of building redboot. Is it right that
> redboot is a simple ecos with a simple application?

Yes, RedBoot is just an eCos application which happens to use only
a [small] portion of the eCos HAL - no kernel, no threads.